Golf ball core compositions

ABSTRACT

Golf ball compositions including novel processing aids, e.g., metal salts of unsaturated fatty acids, high styrene resins, transpolyisoprene, and transpolybutadiene, for inclusion in rubber-based compositions that reduce safety risks, mixer down time, increase dispersion of the ingredients during processing, and increase component COR over that of a component formed with a conventional processing aid.

FIELD OF THE INVENTION

The present invention relates to golf balls. In particular, the golfballs of the invention are formed from, at least in part, novelprocessing aids that reduce safety risks, mixer down time, and increasedispersion of the ingredients during processing. The compositions of theinvention are envisioned for incorporation into any golf ball layer,particularly core layers.

BACKGROUND OF THE INVENTION

Conventional golf balls can be divided into several general classes: (a)solid golf balls having one or more layers, and (b) wound golf balls.Solid golf balls typically include a solid core and at least a cover.Solid cores are generally formed using a rubber-based or elastomericcomposition, typically polybutadiene or the like. The polybutadiene corematerial is usually processed in a two roll mill or Banbury typeinternal mixer, in combination with additional ingredients in order toprovide adequate curing and physical property characteristics. Theadditional ingredients may include, free radicial initiators such asperoxides, cis-to-trans catalysts, crosslinking agents such as metalacrylates, fillers, and the like.

The processability of such a core formulation in a two roll mill orBanbury mixer, however, is affected by certain ingredients. For example,metal acrylates and their interaction with the elastomers and/or theperoxides tend to cause build-up to occur on the rolls, sides of themixer, and on the rotors. This build-up, if not removed after everybatch, generally leads to reduced heat transfer and increased cycletime. Moreover, fragments from the build-up may be mixed into subsequentbatches and result in a non-uniform product.

Numerous methods have been attempted to eliminate the zinc acrylatebuild-up including varying the order of addition of ingredients. Forinstance, the conventional method of combining the core ingredients isto add most of the ingredients to the elastomer all at once andsubsequently add the peroxide. To reduce the build-up from thisconventional method, others have attempted to add the metal acrylatefirst, in order to partially encapsulate the metal acrylate and minimizecontact of the metal acrylate with the other ingredients causing thebuild-up. However, even this order of ingredients only partially reducesthe build-up and has a further disadvantage of increasing the cycletime. Another method, disclosed in U.S. Pat. No. 6,194,504, fullyencapsulates the metal acrylates by contacting the metal acrylate with asolution of polymer in organic solvent, and then removing the solventprior to compounding the encapsulated metal acrylate into theelastomeric mixture.

In addition to the build-up, the conventional dry mixing method ofcombining the core ingredients does not typically provide a very uniformdispersion of the metal acrylate throughout the elastomer.

Furthermore, when transferred, metal acrylates generally produce dustparticles having diameters of about 10 microns, which result in odor andinhalation risks for operators. Likewise, certain cis-to-transcatalysts, such as organosulfur compounds, are also dusty in nature.

Thus, there is a need in the art for a core composition with improvedprocessability and dispersion of the ingredients and reduced safetyrisks. In particular, a there is a need in the art for a corecomposition that includes particular ingredients in pelleted form with aprocessing aid to reduce the odor and inhalation problems associatedwith conventional core compositions and to increase dispersion of theingredients within the elastomeric composition.

SUMMARY OF THE INVENTION

The present invention is directed to a core composition for a golf ballincluding a first base rubber; a crosslinker masterbatch including atleast one crosslinker, a second base rubber, and at least one processingaid, wherein the processing aid is selected from the group consisting ofmetal salts of fatty acids, high styrene resins, transpolyisoprene,transpolybutadiene, and mixtures thereof; and a free radical initiator.

In one embodiment, the processing aid is a metal salt of an unsaturatedfatty acid. The metal salt may include zinc, magnesium, calcium,aluminum, sodium, lithium, nickel, or mixtures thereof. In anotherembodiment, the second base rubber includes polybutadiene.

In this aspect of the invention, the crosslinker masterbatch may includeabout 60 percent to about 90 percent crosslinker, about 10 percent toabout 30 percent base rubber, and about 1 percent to about 10 percentprocessing aid. In one embodiment, the crosslinker masterbatch includesabout 75 percent to about 85 percent crosslinker, about 10 percent toabout 25 percent base rubber, and about 1 percent to about 5 percentprocessing aid.

In another embodiment, the crosslinker is present in a blend with ametal salt of an unsaturated fatty acid. In still another embodiment,the crosslinker includes zinc diacrylate, and wherein the processing aidcomprises a zinc salt of an unsaturated fatty acid. The processing aidmay be selected from the group consisting of zinc stearate, zinc oleate,and mixtures thereof. In addition, the free radical initiator mayinclude a peroxide.

The composition may further include at least one of a density-adjustingfiller or an antioxidant.

In this aspect of the invention, the cover may include one or morehomopolymeric or copolymeric cover materials selected from the groupconsisting of thermoset polyurethane, thermoplastic polyurethane,thermoset polyurea, thermoplastic polyurea, thermoset elastomer,thermoplastic elastomer and thermoplastic ionomer. In one embodiment,the high styrene resins are selected from the group consisting ofstyrene-butadiene copolymers, aliphatic hydrocarbon resins, and mixturesthereof.

The present invention is also directed to a composition for golf ballsincluding a base rubber; a crosslinker pellet, wherein the pelletincludes at least one crosslinking agent and at least one processing aidcomprising a metallic salt of a fatty acid; and a free radicalinitiator. The pellet may include about 50 percent to about 95 percentof the at least one crosslinking agent and about 50 percent to about 5percent of the at least one processing aid.

In one embodiment, the metallic salt is selected from the groupconsisting of magnesium, calcium, zinc, aluminum, sodium, lithium,nickel, and mixtures thereof. In still another embodiment, the fattyacid is oleic acid, stearic acid, or combinations thereof.

In this aspect of the invention, the composition may include about 10pph to about 15 pph of the metallic salt of a fatty acid by weight ofthe composition.

The crosslinking agent may be selected from the group consisting of zincacrylate, zinc diacrylate, zinc methacrylate, zinc dimethacrylate, andmixtures thereof.

The present invention further relates to a method of preparing acomposition for golf balls including the steps of: providing acrosslinking agent; providing a processing aid including a metallic saltof a fatty acid; blending the crosslinking agent and the processing aidin a mixer at a temperature of about 175° F. to about 250° F. to form apellet; providing a base rubber; mixing the base rubber and the pellet;and promoting crosslinking between the base rubber and the pellet with afree radical initiator.

The crosslinking agent may be selected from the group consisting of zincacrylate, zinc diacrylate, zinc methacrylate, zinc dimethacrylate, andmixtures thereof. In one embodiment, the processing aid includes zincstearate, zinc oleate, or mixtures thereof.

The free radical initiator may include di-t-amyl peroxide,di(2-t-butyl-peroxyisopropyl)benzene peroxide or, -bis(t-butylperoxy)diisopropylbenzene, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane or1,1-di(t-butylperoxy) 3,3,5-trimethyl cyclohexane, dicumyl peroxide,di-t-butyl peroxide, 2,5-di-(t-butylperoxy)-2,5-dimethyl hexane,n-butyl-4,4-bis(t-butylperoxy)valerate, lauryl peroxide, benzoylperoxide, t-butyl hydroperoxide, or mixtures thereof.

In one embodiment, the step of blending is performed at a temperature ofabout 200° F. to about 225° F. In another embodiment, the step ofblending further includes blending about 50 percent to about 95 percentcrosslinking agent with about 50 percent to about 5 percent processingaid.

The invention is also directed to a velocity-improving pastille for golfballs including: a chemical peptizer including at least one sulfurcompound; and a physical peptizer including at least one metallic saltof a fatty acid, high styrene resins, transpolyisoprene,transpolybutadiene, and mixtures thereof. The metallic salt may beselected from the group consisting of magnesium, calcium, zinc,aluminum, sodium, lithium, nickel, and mixtures thereof. The fatty acidmay be oleic acid, stearic acid, or combinations thereof.

In one embodiment, the sulfur compound includes at least one halogenatedorganosulfur compound. In another embodiment, the halogenatedorganosulfur compound has the general formula:

where R₁–R₅ are selected from the group consisting of C₁–C₈ alkylgroups; halogen groups; thiol groups (—SH), carboxylated groups;sulfonated groups; hydrogen; pentafluorothiophenol; 2-fluorothiophenol;3-fluorothiophenol; 4-fluorothiophenol; 2,3-fluorothiophenol;2,4-fluorothiophenol; 3,4-fluorothiophenol; 3,5-fluorothiophenol2,3,4-fluorothiophenol; 3,4,5-fluorothiophenol;2,3,4,5-tetrafluorothiophenol; 2,3,5,6-tetrafluorothiophenol;4-chlorotetrafluorothiophenol; pentachlorothiophenol;2-chlorothiophenol; 3-chlorothiophenol; 4-chlorothiophenol;2,3-chlorothiophenol; 2,4-chlorothiophenol; 3,4-chlorothiophenol;3,5-chlorothiophenol; 2,3,4-chlorothiophenol; 3,4,5-chlorothiophenol;2,3,4,5-tetrachlorothiophenol; 2,3,5,6-tetrachlorothiophenol;pentabromothiophenol; 2-bromothiophenol; 3-bromothiophenol;4-bromothiophenol; 2,3-bromothiophenol; 2,4-bromothiophenol;3,4-bromothiophenol; 3,5-bromothiophenol; 2,3,4-bromothiophenol;3,4,5-bromothiophenol; 2,3,4,5-tetrabromothiophenol;2,3,5,6-tetrabromothiophenol; pentaiodothiophenol; 2-iodothiophenol;3-iodothiophenol; 4-iodothiophenol; 2,3-iodothiophenol;2,4-iodothiophenol; 3,4-iodothiophenol; 3,5-iodothiophenol;2,3,4-iodothiophenol; 3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol;2,3,5,6-tetraiodothiophenoland; metal salts thereof; and mixturesthereof. For example, the halogenated organosulfur compound may be zincpentachlorothiophenol. The sulfur compound may be selected from thegroup consisting of diphenyl disulfide; 4,4′-ditolyl disulfide;dibenzamino disulfide; 2,2′-benzamido diphenyl disulfide;bis(2-aminophenyl)disulfide; bis(4-aminophenyl)disulfide;bis(3-aminophenyl)disulfide; 2,2′-bis(4-aminonaphthyl)disulfide;2,2′-bis(3-aminonaphthyl)disulfide; 2,2′-bis(4-aminonaphthyl)disulfide;2,2′-bis(5-aminonaphthyl)disulfide; 2,2′-bis(6-aminonaphthyl) disulfide;2,2′-bis(7-aminonaphthyl)disulfide; 2,2′-bis(8-aminonaphthyl)disulfide;1,1′-bis(2-aminonaphthyl)disulfide; 1,1′-bis(3-aminonaphthyl)disulfide;1,1′-bis(3-aminonaphthyl)disulfide; 1,1′-bis(4-aminonaphthyl)disulfide;1,1′-bis(5-aminonaphthyl) disulfide; 1,1′-bis(6-aminonaphthyl)disulfide;1,1′-bis(7-aminonaphthyl)disulfide; 1,1′-bis(8-aminonaphthyl)disulfide;1,2′-diamino-1,2′-dithiodinaphthalene;2,3′-diamino-1,2′-dithiodinaphthalene; bis(4-chlorophenyl)disulfide;bis(2-chlorophenyl)disulfide; bis(3-chlorophenyl)disulfide;bis(4-bromophenyl)disulfide; bis(2-bromophenyl) disulfide;bis(3-bromophenyl)disulfide; bis(4-fluorophenyl)disulfide;bis(4-iodophenyl) disulfide; bis(2,5-dichlorophenyl)disulfide;bis(3,5-dichlorophenyl)disulfide; bis(2,4-dichlorophenyl)disulfide;bis(2,6-dichlorophenyl)disulfide; bis(2,5-dibromophenyl) disulfide;bis(3,5-dibromophenyl)disulfide; bis(2-chloro-5-bromophenyl)disulfide;bis(2,4,6-trichlorophenyl)disulfide;bis(2,3,4,5,6-pentachlorophenyl)disulfide; bis(4-cyanophenyl)disulfide;bis(2-cyanophenyl)disulfide; bis(4-nitrophenyl)disulfide;bis(2-nitrophenyl)disulfide; 2,2′-dithiobenzoic ethyl;2,2′-dithiobenzoic methyl; 2,2′-dithiobenzoic acid; 4,4′-dithiobenzoicethyl; bis(4-acetylphenyl)disulfide; bis(2-acetylphenyl)disulfide;bis(4-formylphenyl)disulfide; bis(4carbamoylphenyl)disulfide;1,1′-dinaphthyl disulfide; 2,2′-dinaphthyl disulfide; 1,2′-dinaphthyldisulfide; 2,2′-bis(1-chlorodinaphthyl)disulfide;2,2′-bis(1-bromonaphthyl)disulfide; 1,1′-bis(2-chloronaphthyl)disulfide;2,2′-bis(1-cyanonaphtyl)disulfide; 2,2′-bis(1-acetylnaphthyl) disulfide;and mixtures thereof.

In one embodiment, the pastille includes about 50 weight percent toabout 95 weight percent of the chemical peptizer and about 50 weightpercent to about 5 weight percent of physical peptizer. In anotherembodiment, the pastille includes about 70 weight percent to about 80weight percent of the chemical peptizer and about 11 weight percent toabout 13 weight percent of the physical peptizer. The pastille mayfurther include a base rubber present in an amount of about 12 percentto about 15 percent by weight of the pastille.

The present invention also relates to a golf ball including a core and acover, wherein the core includes a velocity-improving pastilleincluding: a chemical peptizer including at least one sulfur compound;and a physical peptizer including at least one metallic salt of a fattyacid. In one embodiment, the physical peptizer includes zinc stearate,zinc oleate, or mixtures thereof. In another embodiment, the chemicalpeptizer is selected from the group consisting of zincpentachlorothiophenol, dibenzaminodisulfide, and mixtures thereof.

The core composition may further include a base rubber, at least onecrosslinking agent, and at least one free radical initiator. In oneembodiment, the core composition further includes a least one of anantioxidant and a density-adjusting filler.

The pastille may include about 50 percent to about 95 percent of thechemical peptizer and about 50 percent to about 5 percent of thephysical peptizer.

The present invention is further directed to a method of preparing avelocity-improving pastille for golf balls including the steps of:providing a chemical peptizer including at least one sulfur compound;providing a physical peptizer including at least one metallic salt of afatty acid; blending the chemical peptizer and physical peptizer in amixer at a temperature of about 175° F. to about 250° F. to form apellet.

In one embodiment, the at least one sulfur compound is selected from thegroup consisting of diphenyl disulfide; 4,4′-ditolyl disulfide;dibenzamino disulfide; 2,2′-benzamido diphenyl disulfide;bis(2-aminophenyl)disulfide; bis(4-aminophenyl) disulfide;bis(3-aminophenyl)disulfide; 2,2′-bis(4-aminonaphthyl)disulfide;2,2′-bis(3-aminonaphthyl)disulfide; 2,2′-bis(4-aminonaphthyl)disulfide;2,2′-bis(5-aminonaphthyl) disulfide; 2,2′-bis(6-aminonaphthyl)disulfide;2,2′-bis(7-aminonaphthyl)disulfide; 2,2′-bis(8-aminonaphthyl)disulfide;1,1′-bis(2-aminonaphthyl)disulfide; 1,1′-bis(3-aminonaphthyl)disulfide;1,1′-bis(3-aminonaphthyl)disulfide; 1,1′-bis(4-aminonaphthyl) disulfide;1,1′-bis(5-aminonaphthyl)disulfide; 1,1′-bis(6-aminonaphthyl)disulfide;1,1′-bis(7-aminonaphthyl)disulfide; 1,1′-bis(8-aminonaphthyl)disulfide;1,2′-diamino-1,2′-dithiodinaphthalene;2,3′-diamino-1,2′-dithiodinaphthalene; bis(4-chlorophenyl) disulfide;bis(2-chlorophenyl)disulfide; bis(3-chlorophenyl)disulfide;bis(4-bromophenyl)disulfide; bis(2-bromophenyl)disulfide;bis(3-bromophenyl)disulfide; bis(4-fluorophenyl)disulfide;bis(4-iodophenyl)disulfide; bis(2,5-dichlorophenyl) disulfide;bis(3,5-dichlorophenyl)disulfide; bis(2,4-dichlorophenyl)disulfide;bis(2,6-dichlorophenyl)disulfide; bis(2,5-dibromophenyl)disulfide;bis(3,5-dibromophenyl) disulfide; bis(2-chloro-5-bromophenyl)disulfide;bis(2,4,6-trichlorophenyl)disulfide;bis(2,3,4,5,6-pentachlorophenyl)disulfide; bis(4-cyanophenyl)disulfide;bis(2-cyanophenyl)disulfide; bis(4-nitrophenyl)disulfide;bis(2-nitrophenyl)disulfide; 2,2′-dithiobenzoic ethyl;2,2′-dithiobenzoic methyl; 2,2′-dithiobenzoic acid; 4,4′-dithiobenzoicethyl; bis(4-acetylphenyl)disulfide; bis(2-acetylphthyl)disulfide;bis(4-formylphenyl)disulfide; bis(4carbamoylphenyl)disulfide;1,1′-dinaphthyl disulfide; 2,2′-dinaphthyl disulfide; 1,2′-dinaphthyldisulfide; 2,2′-bis(1-bromonaphthyl)disulfide;1,1′-bis(2-chloronaphthyl)disulfide; 2,2′-bis(1-cyanonaphthyl)disulfide;2,2′-bis(1-acetylnaphthyl)disulfide; and mixtures thereof.

In another embodiment, the at least one sulfur compound is a zinc saltof:

where R₁–R₅ is selected from the group consisting of C₁–C₈ alkyl groups;halogen groups; thiol groups (—SH), carboxylated groups; sulfonatedgroups; hydrogen; pentafluorothiophenol; 2-fluorothiophenol;3-fluorothiophenol; 4-fluorothiophenol; 2,3-fluorothiophenol;2,4-fluorothiophenol; 3,4-fluorothiophenol; 3,5-fluorothiophenol2,3,4-fluorothiophenol; 3,4,5-fluorothiophenol;2,3,4,5-tetrafluorothiophenol; 2,3,5,6-tetrafluorothiophenol;4-chlorotetrafluorothiophenol; pentachlorothiophenol;2-chlorothiophenol; 3-chlorothiophenol; 4-chlorothiophenol;2,3-chlorothiophenol; 2,4-chlorothiophenol; 3,4-chlorothiophenol;3,5-chlorothiophenol; 2,3,4-chlorothiophenol; 3,4,5-chlorothiophenol;2,3,4,5-tetrachlorothiophenol; 2,3,5,6-tetrachlorothiophenol;pentabromothiophenol; 2-bromothiophenol; 3-bromothiophenol;4-bromothiophenol; 2,3-bromothiophenol; 2,4-bromothiophenol;3,4-bromothiophenol; 3,5-bromothiophenol; 2,3,4-bromothiophenol;3,4,5-bromothiophenol; 2,3,4,5-tetrabromothiophenol;2,3,5,6-tetrabromothiophenol; pentaiodothiophenol; 2-iodothiophenol;3-iodothiophenol; 4-iodothiophenol; 2,3-iodothiophenol;2,4-iodothiophenol; 3,4-iodothiophenol; 3,5-iodothiophenol;2,3,4-iodothiophenol; 3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol;2,3,5,6-tetraiodothiophenoland; metal salts thereof; and mixturesthereof.

In this aspect of the invention, the physical peptizer may include zincstearate, zinc oleate, or mixtures thereof.

In one embodiment, the step of blending is performed at a temperature ofabout 200° F. to about 225° F. In another embodiment, the step ofblending further includes 10 blending about 50 percent to about 95percent chemical peptizer with about 50 percent to about 5 percentphysical peptizer.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention can be ascertained fromthe following detailed description that is provided in connection withthe drawings described below:

FIG. 1 is a cross-sectional view of a two layer ball, wherein at least aportion of the golf ball is formed from the compositions of theinvention;

FIG. 2 is a cross-sectional view of a multi-component golf ball, whereinat least a portion of the golf ball is formed from the compositions ofthe invention;

FIG. 3 is a cross-sectional view of a multi-component golf ballincluding a large core, an intermediate layer, and a thin outer coverlayer disposed thereon, wherein at least a portion of the golf ball isformed from the compositions of the invention;

FIG. 4 is a cross-sectional view of a multi-component golf ballincluding a core, an outer core layer, a thin inner cover layer, and athin outer cover layer disposed thereon, wherein at least a portion ofthe golf ball is formed from the compositions of the invention; and

FIG. 5 is a graph depicting the relationship between compression and CORwhen using different processing aids in the zinc diacrylate masterbatchaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an improved composition for use in golfballs. In particular, the present invention relates to a corecomposition including novel processing aids to increase dispersion,increase processing safety, and decrease the negative effects on coreproperties that typically result from use of conventional coreingredients.

The compositions of the present invention may be used in any type ofgolf ball, e.g., one-piece balls, two-piece balls, and multilayer balls.And, while the disclosure is primarily focused on the use of thecomposition and the components thereof in the core of a golf ball, theimproved composition is contemplated for use in any layer of a golfball.

Compositions of the Invention

As briefly discussed above, the present invention is focused primarilyon novel processing aids that increase dispersion, decrease safety risksduring processing, and reduce the negative effects that conventionalprocessing aids have on the properties of the composition onceincorporated into a golf ball component. Suitable compositions useful tosuch objectives according to the present invention include compositionshaving a base (unvulcanized) rubber, such as compositions based onpolybutadiene, including those based on polybutadiene mixed with otherelastomers. One representative composition of the invention preferablycontains a base rubber, at least one crosslinking agent dispersed in anovel carrier/processing aid, a free radical initiator to promotecrosslinking of the crosslinking agent and the base rubber, and a fillerto control the specific gravity.

In an alternate embodiment, the crosslinking agent is a part of acrosslinker masterbatch that includes a processing aid to improve themasterbatch release from the mixer, aid in extrusion of pellets, andavoid pellet compaction in bulk containers.

The present invention also relates to velocity improving pastilles thatinclude at least one sulfur compound and at least one of the processingaids of the invention.

Base Rubber

The base rubber preferably has a relatively high molecular weight, e.g.,about 100,000 to about 500,000, more preferably about 200,000 to about500,000. As used herein, the term “molecular weight” is defined as theabsolute weight average molecular weight. In one embodiment, the baserubber molecular weight is greater than about 250,000, and morepreferably from about 300,000 to 500,000. In another embodiment, thebase rubber molecular weight is about 400,000 or greater and thepolydispersity is no greater than about 2.

In addition, the base rubber preferably has a high-Mooney-viscosity. Inone embodiment, the base rubber has a Mooney viscosity greater thanabout 20, preferably greater than about 30, and more preferably greaterthan about 40. Mooney viscosity is typically measured according to ASTMD-1646. In one embodiment, the Mooney viscosity of the base rubber isabout 50 or greater. In another embodiment, the base rubber has a Mooneyviscosity of about 40 to about 80. In still another embodiment, theMooney viscosity is from about 45 to about 60, more preferably fromabout 45 to about 55.

In one embodiment, the base rubber is 1,4-polybutadiene, preferablyhaving a cis-isomer content of about 40 percent or greater. As usedherein, unless otherwise stated, the percent of cis-isomerpolybutadiene, reflects the amount of cis-isomer compared to the totalnumber of polybutadiene isomers. The fraction is multiplied by 100 toobtain the percent. The percent of trans-isomer and vinyl-isomer,discussed below, is similarly defined. In one embodiment, the cis-isomeris present in an amount of greater than about 70 percent of the totalpolybutadiene content, preferably greater than about 80 percent of thetotal polybutadiene content, and more preferably greater than about 90percent of the total polybutadiene content. In still another embodiment,the cis-isomer is present in an amount of greater than about 95 percent,and more preferably greater than about 96 percent, of the totalpolybutadiene content.

Examples of desirable polybutadiene rubbers include BUNA® CB22 and BUNA®CB23, commercially available from Bayer of Akron, Ohio; UBEPOL® 360L andUBEPOL® 150L, commercially available from UBE Industries of Tokyo,Japan; and CARIFLEX® BCP820 and CARIFLEX® BCP824, commercially availablefrom Shell of Houston, Tex. In addition, the base rubber may be mixedwith other elastomers known in the art such as natural rubber,polyisoprene rubber and/or styrene-butadiene rubber in order to modifythe properties of the composition.

Crosslinking Agent(s)

Crosslinkers are generally included in the core formulation to crosslinka portion of the chains of polymers in the resilient polymer component.For example, the desired compression may be obtained by adjusting theamount of crosslinking, which may be achieved by altering the type andamount of crosslinking agent, a method well-known to those of ordinaryskill in the art. The crosslinking agent(s) is preferably contained inpellet form with at least one carrier/processing aid to reduce dusthandling problems and other safety issues and reduce mixer build up whenmixing the compositions of the invention. In addition, the processingaid increases dispersion of the crosslinking agent.

In one embodiment, the crosslinker is present in an amount of about 10parts per hundred to about 50 parts per hundred based on 100 parts baserubber. As used herein, the term parts per hundred (pph) is defined asthe number of parts by weight of a particular component present in amixture, relative to 100 parts by weight of the total polymer component.Mathematically, this can be expressed as the weight of an ingredientdivided by the total weight of the polymer, multiplied by a factor of100. In another embodiment, about 20 pph to about 40 pph of thecrosslinker is present in the composition. In still another embodiment,the crosslinker is present in the composition in an amount of about 25pph to about 35 pph.

Suitable crosslinking agents include one or more metallic salts ofunsaturated fatty acids having 3 to 8 carbon atoms, such as acrylic ormethacrylic acid, or monocarboxylic acids, such as zinc, calcium, ormagnesium acrylate salts, and the like, and mixtures thereof. Examplesinclude, but are not limited to, one or more metal salt diacrylates,dimethacrylates, and monomethacrylates, wherein the metal is magnesium,calcium, zinc, aluminum, sodium, lithium, or nickel. Preferred acrylatesinclude zinc acrylate, zinc diacrylate (ZDA), zinc methacrylate (ZMA),zinc dimethacrylate (ZDMA), and mixtures thereof.

In one embodiment, the crosslinking agent is zinc diacrylate, which ispreferably present in a masterbatch, wherein the amount of themasterbatch is from about 25 pph to about 35 pph of the totalcomposition. This embodiment is particularly applicable when anorganosulfur compound is selected as the cis-to-trans catalyst, whichwill be discussed in more detail below.

Because certain crosslinkers have negative effects on the processing ofrubber-based compositions and the resultant composition properties, thecrosslinkers included in the compositions of the invention arepreferably dispersed in a pellet or pastille of a processing aidaccording to the invention, referred to herein as a crosslinkermasterbatch. As mentioned above, the incorporation of the crosslinkerwith a processing aid of the invention reduces dust handling problemsand improves dispersion of the crosslinker within the base rubberformulation.

The processing aid may be any metallic salt of a fatty acid that acts asa dispersion aid and/or acid acceptor. The metallic salt of a fatty acidis preferably a metallic salt of an unsaturated fatty acid, wherein themetal is magnesium, calcium, zinc, aluminum, sodium, lithium, nickel, ormixtures thereof. In one embodiment, the fatty acid is oleic acid,stearic acid, or combinations thereof. In another embodiment, the metalis zinc. In yet another embodiment, suitable metallic salts of a fattyacids include zinc stearate, zinc oleate, or mixtures thereof. Anon-limiting example of a suitable metallic salt of a fatty acid for usewith the invention is Aktiplast®, which is commercially available fromRhein Chemie of Trenton, N.J. Aktiplast® products are mainly for naturalrubber blend compounds and typically zinc salts of unsaturated fattyacids. One additional advantage of the Aktiplast® is that, whenincorporated into a base rubber composition, it acceleratesvulcanization.

In this aspect of the invention, the processing aid is preferablypresent in the compositions of the invention in an amount of about 15pph or less. In one embodiment, the processing aid is present in thecompositions of the invention in an amount of about 5 pph or greater. Inanother embodiment, about 10 pph to about 15 pph of processing aid isincluded in the compositions of the invention.

In addition, the processing aid may be a thermoplastic material, such ashigh styrene resin, trans-polyisoprene, or trans-polybutadiene. Forexample, the processing aid may include styrene-butadiene copolymers,aliphatic hydrocarbon resins, and mixtures thereof. Suitablecommercially available high styrene resins include, but are not limitedto, Andrez® 8000 A-E and Westco® HSR, manufactured by Western ReserveChemical, Inc. of Stow, Ohio.

The crosslinker/processing aid pellet may be made in any manner thatresults in a crosslinker dispersed in a processing aid pellet. Onesuitable method includes blending the processing aid and crosslinker ina mixer heated to about 175° F. to about 250° F., preferably from about200° F. to about 225° F. The resultant pellets preferably include about50 percent to about 95 percent crosslinker by weight of the total pelletand about 50 percent to about 5 percent of the processing aid. In oneembodiment, about 60 percent or greater of the pellet is crosslinker and40 percent or less is the processing aid.

Another method of incorporating the crosslinker into a pellet form withthe processing aid is to create a crosslinker masterbatch that is laterincorporated into the rubber-based composition. For example, acrosslinker masterbatch according to the invention may includecrosslinker, a small amount of base rubber, and a processing aid. Inparticular, the masterbatch preferably includes about 60 percent toabout 90 percent crosslinker, about 10 percent to about 30 percent baserubber, and about 1 percent to about 10 percent processing aid. In oneembodiment, the masterbatch includes about 75 percent to about 85percent crosslinker, about 10 percent to about 25 percent base rubber,and about 1 percent to about 5 percent processing aid. For example, amasterbatch according to the invention may include about 80 percentcrosslinker, about 17 percent base rubber, and about 3 percentprocessing aid. This masterbatch formulation is particularly useful withzinc diacrylate as the crosslinker, polybutadiene as the base rubber,and at least one of the metal salts of fatty acids or thermoplasticprocessing aids discussed above.

In addition, the crosslinker may include a processing aid before beingincorporated into the masterbatch. In one embodiment, the weightpercentage of the crosslinker with regard to the masterbatch includes anpredetermined amount of crosslinker and processing aid. For instance,the 80 percent crosslinker to be included in the masterbatch formulationmay include about 90 percent to about 99 percent zinc diacrylate andabout 10 percent to about 1 percent of a metal salt of a fatty acid. Themetal salt of a fatty acid is preferably zinc stearate in this aspect ofthe invention.

After the masterbatch formulation is made, it is mixed with the baserubber, free radical initiator and, optionally, cis-to-trans catalystand/or filler(s).

Velocity Improving Pastilles

The compositions of the invention may also include a velocity improvingpastille, i.e., a pastille including a chemical peptizer and a physicalpeptizer. The chemical pastille is preferably a sulfur compound and thephysical peptizer, i.e., the processing aid, is preferably a metal saltof an unsaturated fatty acid. As above, the processing aid will aid indispersion of the velocity improver, and also act as an acid acceptor.

The sulfur compound may be a halogenated organosulfur compoundsincluding, but not limited to those having the following generalformula:

where R₁–R₅ can be C₁–C₈ alkyl groups; halogen groups; thiol groups(—SH), carboxylated groups; sulfonated groups; and hydrogen; in anyorder; and also pentafluorothiophenol; 2-fluorothiophenol;3-fluorothiophenol; 4-fluorothiophenol; 2,3-fluorothiophenol;2,4-fluorothiophenol; 3,4-fluorothiophenol; 3,5-fluorothiophenol2,3,4-fluorothiophenol; 3,4,5-fluorothiophenol;2,3,4,5-tetrafluorothiophenol; 2,3,5,6-tetrafluorothiophenol;4-chlorotetrafluorothiophenol; pentachlorothiophenol;2-chlorothiophenol; 3-chlorothiophenol; 4-chlorothiophenol;2,3-chlorothiophenol; 2,4-chlorothiophenol; 3,4-chlorothiophenol;3,5-chlorothiophenol; 2,3,4-chlorothiophenol; 3,4,5-chlorothiophenol;2,3,4,5-tetrachlorothiophenol; 2,3,5,6-tetrachlorothiophenol;pentabromothiophenol; 2-bromothiophenol; 3-bromothiophenol;4-bromothiophenol; 2,3-bromothiophenol; 2,4-bromothiophenol;3,4-bromothiophenol; 3,5-bromothiophenol; 2,3,4-bromothiophenol;3,4,5-bromothiophenol; 2,3,4,5-tetrabromothiophenol;2,3,5,6-tetrabromothiophenol; pentaiodothiophenol; 2-iodothiophenol;3-iodothiophenol; 4-iodothiophenol; 2,3-iodothiophenol;2,4-iodothiophenol; 3,4-iodothiophenol; 3,5-iodothiophenol;2,3,4-iodothiophenol; 3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol;2,3,5,6-tetraiodothiophenoland; and their metal salts.

For example, the halogenated organosulfur compound may bepentachlorothiophenol, which is commercially available in neat form(commercially available from eChinachem of San Francisco, Calif.) orunder the tradename STRUKTOL® A-95, a clay-based carrier containing thesulfur compound pentachlorothiophenol loaded at 45 percent (commerciallyavailable from Struktol Company of America of Stow, Ohio). In oneembodiment, the halogenated organosulfur compound is the zinc salt ofpentachlorothiophenol (ZnPCTP), which is also commercially availablefrom eChinachem of San Francisco, Calif.

In another embodiment, the velocity improver may include diphenyldisulfide; 4,4′-ditolyl disulfide; dibenzamino disulfide; 2,2′-benzamidodiphenyl disulfide; bis(2-aminophenyl)disulfide;bis(4-aminophenyl)disulfide; bis(3-aminophenyl)disulfide;2,2′-bis(4-aminonaphthyl)disulfide; 2,2′-bis(3-aminonaphthyl)disulfide;2,2′-bis(4-aminonaphthyl)disulfide; 2,2′-bis(5-aminonaphthyl)disulfide;2,2′-bis(6-aminonaphthyl) disulfide; 2,2′-bis(7-aminonaphthyl)disulfide;2,2′-bis(8-aminonaphthyl)disulfide; 1,1′-bis(2-aminonaphthyl)disulfide;1,1′-bis(3-aminonaphthyl)disulfide; 1,1′-bis(3-aminonaphthyl)disulfide;1,1′-bis(4-aminonaphthyl)disulfide; 1,1′-bis(5-aminonaphthyl) disulfide;1,1′-bis(6-aminonaphthyl)disulfide; 1,1′-bis(7-aminonaphthyl)disulfide;1,1′-bis(8-aminonaphthyl)disulfide;1,2′-diamino-1,2′-dithiodinaphthalene;2,3′-diamino-1,2′-dithiodinaphthalene; bis(4-chlorophenyl)disulfide;bis(2-chlorophenyl)disulfide; bis(3-chlorophenyl)disulfide;bis(4-bromophenyl)disulfide; bis(2-bromophenyl) disulfide;bis(3-bromophenyl)disulfide; bis(4-fluorophenyl)disulfide;bis(4-iodophenyl) disulfide; bis(2,5-dichlorophenyl)disulfide;bis(3,5-dichlorophenyl)disulfide; bis(2,4-dichlorophenyl)disulfide;bis(2,6-dichlorophenyl)disulfide; bis(2,5-dibromophenyl) disulfide;bis(3,5-dibromophenyl)disulfide; bis(2-chloro-5-bromophenyl)disulfide;bis(2,4,6-trichlorophenyl)disulfide;bis(2,3,4,5,6-pentachlorophenyl)disulfide; bis(4-cyanophenyl)disulfide;bis(2-cyanophenyl)disulfide; bis(4-nitrophenyl)disulfide;bis(2-nitrophenyl)disulfide; 2,2′-dithiobenzoic ethyl;2,2′-dithiobenzoic methyl; 2,2′-dithiobenzoic acid; 4,4′-dithiobenzoicethyl; bis(4-acetylphenyl)disulfide; bis(2-acetylphenyl)disulfide;bis(4-formylphenyl)disulfide; bis(4carbamoylphenyl)disulfide;1,1′-dinaphthyl disulfide; 2,2′-dinaphthyl disulfide; 1,2′-dinaphthyldisulfide; 2,2′-bis(1-chlorodinaphthyl)disulfide;2,2′-bis(1-bromonaphthyl)disulfide; 1,1′-bis(2-chloronaphthyl)disulfide;2,2′-bis(1-cyanonaphtyl)disulfide; 2,2′-bis(1-acetylnaphthyl) disulfide;and the like; or a mixture thereof. In one embodiment, the organosulfurcomponents include diphenyl disulfide, 4,4′-ditolyl disulfide, or amixture thereof. Dibenzaminodisulfide is particularly useful as a sulfurcompound according to this embodiment.

The chemical peptizer is preferably present in an amount of about 60percent to about 90 percent by weight of the pastille composition. Inone embodiment, the pastille composition includes about 65 percent toabout 80 percent by weight chemical peptizer, more preferably about 70percent to about 80 percent. In another embodiment, the chemicalpeptizer is present in the pastille composition in an amount of about 75percent.

The processing aid may be any metal salt of a fatty acid that acts as anacid acceptor and aids in dispersion of the sulfur compound. In oneembodiment, the fatty acid is oleic acid, stearic acid, or combinationsthereof. In another embodiment, the metal may be magnesium, calcium,zinc, aluminum, sodium, lithium, or nickel. In still another embodiment,the metal is zinc. For example, suitable metallic salts of fatty acidsinclude zinc stearate, zinc oleate, or mixtures thereof. The fatty acidsalts are preferably included in an amount of about 10 percent to about15 percent by weight of the pastille composition. In one embodiment, thephysical peptizer may be present in an amount of about 11 percent toabout 14 percent by weight of the pastille composition, preferably about11 percent to about 13 percent. For example, the pastille compositionmay include about 12 percent by weight fatty acid salt.

The pastille may also include a base rubber, such as polybutadiene. Whenincluded, the base rubber may be present in an amount of about 5 percentto about 30 percent by weight of the pastille composition. In oneembodiment, the pastille composition includes about 10 percent to about25 percent by weight base rubber, more preferably about 10 percent toabout 20 percent. In another embodiment, the base rubber is present inthe pastille composition in an amount of about 12 percent to about 15percent by weight of the pastille composition. For example, the pastillecomposition may include about 13 percent base rubber.

The pastille may be made in any manner that results in a blend of thesulfur compounds and processing aids discussed above. One suitablemethod includes blending the processing aid and crosslinker in a mixerheated to about 175° F. to about 250° F., preferably from about 200° F.to about 225° F. The resultant pellets preferably include about 50percent to about 95 percent sulfur compound and about 50 percent toabout 5 percent of the processing aid. In one embodiment, the velocityimproving pastille includes about 50 percent to about 95 percent ZnPCTPand about 50 percent to about 5 percent zinc stearate.

Free Radical Source(s)

A free-radical source, or free-radical initiator, is used to promotecrosslinking between the crosslinker and the base rubber. Thus, the freeradical source is preferably present in an amount sufficient to promotecrosslinking.

In one embodiment, about 0.1 pph or greater of the free radical source,based on 100 part of the base rubber, is present in the composition. Inanother embodiment, the free radical source is present in an amount ofabout 0.1 pph to about 15 pph. In still another embodiment, the freeradical source is present in an amount of about 0.2 pph to about 5 pph,preferably about 0.25 pph to about 2.5 pph. In yet another embodiment,the free radical source is present in an amount of about 0.5 pph toabout 2 pph. In still another embodiment, the amount of free radicalsource is about 1 pph or less, preferably about 0.9 pph or less.

The free-radical source is typically a peroxide, and preferably anorganic peroxide, which decomposes during the cure cycle. Suitablefree-radical sources include organic peroxide compounds, such asdi-t-amyl peroxide, di(2-t-butyl-peroxyisopropyl)benzene peroxide or,-bis(t-butylperoxy) diisopropylbenzene,1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane or1,1-di(t-butylperoxy) 3,3,5-trimethyl cyclohexane, dicumyl peroxide,di-t-butyl peroxide, 2,5-di-(t-butylperoxy)-2,5-dimethyl hexane,n-butyl-4,4-bis(t-butylperoxy)valerate, lauryl peroxide, benzoylperoxide, t-butyl hydroperoxide, and the like, and any mixture thereof.

Other examples include, but are not limited to, VAROX® 231 XL and Varox®DCP-R, commercially available from Elf Atochem of Philadelphia, Pa.;PERKODOX® BC, PERKODOX® 14, and TRIGONOX® 265, commercially availablefrom Akzo Nobel of Chicago, Ill.; and ELASTOCHEM® DCP-70, commerciallyavailable from Rhein Chemie of Trenton, N.J.

It is well known that peroxides are available in a variety of formshaving different activity. The activity is typically defined by the“active oxygen content.” For example, PERKODOX® BC peroxide is 98percent active and has an active oxygen content of 5.8 percent, whereasPERKODOX® DCP-70 is 70 percent active and has an active oxygen contentof 4.18 percent.

If the peroxide is present in pure form, it is preferably present in anamount of at least about 0.25 pph, more preferably between about 0.35pph and about 2.5 pph, and most preferably between about 0.5 pph andabout 2 pph. Peroxides are also available in concentrate form, which arewell-known to have differing activities, as described above. In thiscase, if concentrate peroxides are employed in the present invention,one skilled in the art would know that the concentrations suitable forpure peroxides are easily adjusted for concentrate peroxides by dividingby the activity. For example, 2 pph of a pure peroxide is equivalent 4pph of a concentrate peroxide that is 50 percent active (i.e., 2 dividedby 0.5=4).

The free radical source may alternatively or additionally be one or moreof an electron beam, UV or gamma radiation, x-rays, or any other highenergy radiation source capable of generating free radicals. It shouldbe further understood that heat often facilitates initiation of thegeneration of free radicals.

Cis-to-Trans Catalyst

The compositions of the invention may also includes at least onecis-to-trans catalyst to at least partially convert the cis-isomers inthe base rubber to trans-isomers. When included, the cis-to-transcatalyst is preferably contained in pellet form with at least one of thenovel carriers/processing aids discussed above with respect to thecrosslinker pellet and/or masterbatch.

Suitable cis-to-trans catalysts, and methods of incorporating thecatalysts into the present formulations, are disclosed in U.S. PatentPublication No. 2003/0119989, which is incorporated by reference in itsentirety herein. In particular, a high molecular weightcis-1,4-polybutadiene is converted to increase the percentage oftrans-isomer content at any point in the golf ball or portion thereof,preferably to increase the percentage throughout substantially all ofthe golf ball or portion thereof, during the molding cycle.

Without being bound by any particular theory, it is believed that thecis-to-trans catalyst component, in conjunction with the free radicalsource, acts to convert a percentage of the polybutadiene polymercomponent from the cis- to the trans-conformation. Thus, formulationsrequiring cis-to-trans conversion require the presence of a cis-to-transcatalyst, such as an organosulfur or metal-containing organosulfurcompound, a substituted or unsubstituted aromatic organic compound thatdoes not contain sulfur or metal, an inorganic sulfide compound, anaromatic organometallic compound, or mixtures thereof.

As used herein, “cis-to-trans catalyst” means any component or acombination thereof that will convert at least a portion of cis-isomerto trans-isomer at a given temperature. The cis-to-trans catalystcomponent may include one or more cis-to-trans catalysts describedherein, but typically includes at least one organosulfur component, aGroup VIA component, an inorganic sulfide, or a combination thereof. Asused herein when referring to the invention, the term “organosulfurcompound(s)” or “organosulfur component(s),” refers to any compoundcontaining carbon, hydrogen, and sulfur. As used herein, the term“sulfur component” means a component that is elemental sulfur, polymericsulfur, or a combination thereof. It should be further understood that“elemental sulfur” refers to the ring structure of S₈ and that“polymeric sulfur” is a structure including at least one additionalsulfur relative to the elemental sulfur.

The cis-to-trans catalyst is typically present in an amount sufficientto produce the reaction product so as to increase thetrans-polybutadiene isomer content to contain from about 5 percent to 70percent trans-isomer polybutadiene based on the total resilient polymercomponent. Therefore, the cis-to-trans catalyst is preferably present inan amount from about 0.1 pph to about 15 pph based on 100 parts baserubber. In one embodiment, the cis-to-trans catalyst is present in anamount from about 0.1 pph to about 10 pph of the total resilient polymercomponent, preferably about 0.1 pph to about 6 pph, more preferablyabout 0.1 pph to about 4 pph, and even more preferably about 0.1 pph toabout 3 pph. In another embodiment, the cis-to-trans catalyst is presentin an amount of about 3 pph or less, preferably about 2.5 pph or less.

The cis-to-trans catalyst may also be incorporated into a pellet orpastille of a processing aid, similar to the crosslinker/processing aidpellets discussed above. When the cis-to-trans catalyst is incorporatedin pellet form with the processing aid, dust handling problems arereduced, and the processing aid allows the cis-to-catalyst to betterdisperse within the base rubber composition. In one embodiment, theprocessing aid is a metal salt of a fatty acid.

The cis-to-trans catalyst/processing aid pellet may be made in anymanner that results in adequate dispersion of the cis-to-trans catalystin the processing aid. One suitable method includes blending theprocessing aid and cis-to-trans catalyst in a mixer heated to about 175°F. to about 250° F., preferably from about 200° F. to about 225° F. Theresultant pellets preferably include about 50 percent to about 95percent catalyst by weight of the total pellet and about 50 percent toabout 5 percent of the processing. In one embodiment, about 60 percentor greater of the pellet is catalyst and 40 percent or less is theprocessing aid. In this aspect of the invention, the processing aid ispreferably present in the compositions of the invention in an amount ofabout 15 pph or less. In one embodiment, the processing aid is presentin the compositions of the invention in an amount of about 5 pph orgreater. In another embodiment, about 10 pph to about 15 pph ofprocessing aid is included in the compositions of the invention.

When an organosulfur cis-to-trans catalyst is used with the presentinvention, it is preferably present in an amount sufficient to producethe reaction product so as to contain at least about 10 percenttrans-isomer at any location, preferably greater than about 15 percenttrans-isomer polybutadiene at any location, and even more preferablyabout 20 percent or greater trans-isomer. In one embodiment, theorganosulfur cis-to-trans catalyst is present in an amount sufficient toproduce the reaction product so as to contain at least about 25 percenttrans-isomer at any location, more preferably at least about 30 percent,and even more preferably at least about 35 percent. Even greater amountsof the cis-to-trans catalyst may be used to produce even higher amountsof trans-isomer. For instance, the cis-to-trans catalyst may be presentin an amount sufficient to produce the reaction product so as to containat least about 38 percent trans-isomer at any location, more preferablyat least about 40 percent, and even more preferably at least about 45percent.

The reaction product may also contain a low amount of 1,2-polybutadiene(vinyl polybutadiene). In one embodiment, the vinyl content is less thanabout 7 percent. In another embodiment, less than about 4 percent vinylisomer is present, more preferably less than about 2 percent.

In one embodiment, the organosulfur cis-to-trans catalyst is present inthe reaction product in an amount from about 0.5 pph or greater. Inanother embodiment, the cis-to-trans catalyst including organosulfurcis-to-trans catalyst is present in the reaction product in an amountfrom about 0.6 pph or greater, preferably about 1.0 pph or greater, andmore preferably about 2.0 pph or greater.

The organosulfur compounds or components contemplated for use with thepresent invention includes aromatic organosulfur components, such asaryl compounds. For example, the organosulfur components that may beused with the present invention include, but are not limited to,diphenyl disulfide; 4,4′-ditolyl disulfide; dibenzamino disulfide;2,2′-benzamido diphenyl disulfide; bis(2-aminophenyl)disulfide;bis(4-aminophenyl)disulfide; bis(3-aminophenyl)disulfide;2,2′-bis(4-aminonaphthyl) disulfide; 2,2′-bis(3-aminonaphthyl)disulfide;2,2′-bis(4-aminonaphthyl)disulfide; 2,2′-bis(5-aminonaphthyl)disulfide;2,2′-bis(6-aminonaphthyl)disulfide; 2,2′-bis(7-aminonaphthyl)disulfide;2,2′-bis(8-aminonaphthyl)disulfide; 1,1′-bis(2-aminonaphthyl) disulfide;1,1′-bis(3-aminonaphthyl)disulfide; 1,1′-bis(3-aminonaphthyl)disulfide;1,1′-bis(4-aminonaphthyl)disulfide; 1,1′-bis(5-aminonaphthyl)disulfide;1,1′-bis(6-aminonaphthyl)disulfide; 1,1′-bis(7-aminonaphthyl)disulfide;1,1′-bis(8-aminonaphthyl) disulfide;1,2′-diamino-1,2′-dithiodinaphthalene;2,3′-diamino-1,2′-dithiodinaphthalene; bis(4-chlorophenyl)disulfide;bis(2-chlorophenyl)disulfide; bis(3-chlorophenyl) disulfide;bis(4-bromophenyl)disulfide; bis(2-bromophenyl)disulfide;bis(3-bromophenyl)disulfide; bis(4-fluorophenyl)disulfide;bis(4-iodophenyl)disulfide; bis(2,5-dichlorophenyl)disulfide;bis(3,5-dichlorophenyl)disulfide; bis(2,4-dichlorophenyl)disulfide;bis(2,6-dichlorophenyl)disulfide; bis(2,5-dibromophenyl) disulfide;bis(3,5-dibromophenyl)disulfide; bis(2-chloro-5-bromophenyl)disulfide;bis(2,4,6-trichlorophenyl)disulfide;bis(2,3,4,5,6-pentachlorophenyl)disulfide; bis(4-cyanophenyl)disulfide;bis(2-cyanophenyl)disulfide; bis(4-nitrophenyl)disulfide;bis(2-nitrophenyl)disulfide; 2,2′-dithiobenzoic ethyl;2,2′-dithiobenzoic methyl; 2,2′-dithiobenzoic acid; 4,4′-dithiobenzoicethyl; bis(4-acetylphenyl)disulfide; bis(2-acetylphenyl)disulfide;bis(4-formylphenyl)disulfide; bis(4carbamoylphenyl)disulfide;1,1′-dinaphthyl disulfide; 2,2′-dinaphthyl disulfide; 1,2′-dinaphthyldisulfide; 2,2′-bis(1-chlorodinaphthyl)disulfide;2,2′-bis(1-bromonaphthyl)disulfide; 1,1′-bis(2-chloronaphthyl)disulfide;2,2′-bis(1-cyanonaphtyl)disulfide; 2,2′-bis(1-acetylnaphthyl) disulfide;and the like; or a mixture thereof. In one embodiment, the organosulfurcomponents include diphenyl disulfide, 4,4′-ditolyl disulfide, or amixture thereof.

The organosulfur components may or may not contain metal, depending onthe desired golf ball component formulation properties. Suitablemetal-containing organosulfur components include, but are not limitedto, cadmium, copper, lead, and tellurium analogs ofdiethyldithiocarbamate, diamyldithiocarbamate, anddimethyldithiocarbamate, or mixtures thereof. When used, themetal-containing organosulfur cis-to-trans catalyst is preferablypresent in the reaction product in an amount from about 1.0 pph orgreater, preferably about 2.0 pph or greater, more preferably about 2.5pph or greater, and even more preferably about 3.0 pph or greater.

In one embodiment, the organosulfur component is substantially free ofmetal. As used herein, the term “substantially free of metal” means lessthan about 10 weight percent, preferably less than about 5 weightpercent, more preferably less than about 3 weight percent, even morepreferably less than about 1 weight percent, and most preferably lessthan about 0.01 weight percent. Suitable substituted or unsubstitutedaromatic organic components that do not include sulfur or a metalinclude, but are not limited to, diphenyl acetylene, azobenzene, or amixture thereof. The aromatic organic group preferably ranges in sizefrom C₆ to C₂₀, and more preferably from C₆ to C₁₀.

In another embodiment, organosulfur component is a halogenatedorganosulfur compound such as those listed above with respect to thevelocity improving pastilles. When used, the halogenated organosulfurcompounds of the present invention are preferably present in an amountgreater than about 1 pph, more preferably between about 2 pph and about5 pph, and most preferably between about 2.2 pph and about 4 pph.

As briefly mentioned above, the cis-to-trans catalyst may also include aGroup VIA component. As used herein, the terms “Group VIA component” or“Group VIA element” refer to a component that includes a sulfurcomponent, selenium, tellurium, or a combination thereof. Elementalsulfur and polymeric sulfur are commercially available from, e.g.,Elastochem, Inc. of Chardon, Ohio. Suitable sulfur catalyst compoundsinclude, but are not limited to, PB(RM-S)-80 elemental sulfur andPB(CRST)-65 polymeric sulfur, each of which is available fromElastochem, Inc. Suitable tellurium and selenium catalysts are availableunder the tradenames TELLOY and VANDEX, respectively, each of which arecommercially available from RT Vanderbilt of Norwalk, Conn.

When used, the cis-to-trans catalyst including a Group VIA component mayis preferably present in the reaction product in an amount from about0.25 pph or greater, preferably about 0.5 pph or greater, and morepreferably about 1.0 pph or greater.

In addition, inorganic sulfide components are contemplated ascis-to-trans catalysts. Suitable inorganic sulfide components for usewith the present invention include, but are not limited to titaniumsulfide, manganese sulfide, and sulfide analogs of iron, calcium,cobalt, molybdenum, tungsten, copper, selenium, yttrium, zinc, tin, andbismuth.

A cis-to-trans catalyst including an inorganic sulfide component ispreferably present in an amount of about 0.5 pph or greater, preferablyabout 0.75 pph or greater, and more preferably about 1.0 pph or greater.

When a reaction product includes a blend of cis-to-trans catalystsincluding an organosulfur component and an inorganic sulfide component,the organosulfur component is preferably present in an amount from about0.5 pph or greater, preferably 1.0 pph or greater, and more preferablyabout 1.5 pph or greater and the inorganic sulfide component ispreferably present in an amount from about 0.5 pph or greater,preferably 0.75 pph or greater, and more preferably about 1.0 pph orgreater.

Furthermore, a substituted or unsubstituted aromatic organic compoundmay also be included in the cis-to-trans catalyst. In one embodiment,the aromatic organic compound is substantially free of metal. Suitablesubstituted or unsubstituted aromatic organic components include, butare not limited to, components having the formula (R₁)_(x)—R₃-M-R₄—(R₂₎_(y), wherein R₁ and R₂ are each hydrogen or a substituted orunsubstituted C₁₋₂₀ linear, branched, or cyclic alkyl, alkoxy, oralkylthio group, or a single, multiple, or fused ring C₆ to C₂₄ aromaticgroup; x and y are each an integer from 0 to 5; R₃ and R₄ are eachselected from a single, multiple, or fused ring C₆ to C₂₄ aromaticgroup; and M includes an azo group or a metal component. R₃ and R₄ areeach preferably selected from a C₆ to C₁₀ aromatic group, morepreferably selected from phenyl, benzyl, naphthyl, benzamido, andbenzothiazyl. R₁ and R₂ are each preferably selected from a substitutedor unsubstituted C₁₋₁₀ linear, branched, or cyclic alkyl, alkoxy, oralkylthio group or a C₆ to C₁₀ aromatic group. When R₁, R₂, R₃, or R₄,are substituted, the substitution may include one or more of thefollowing substituent groups: hydroxy and metal salts thereof; mercaptoand metal salts thereof; halogen; amino, nitro, cyano, and amido;carboxyl including esters, acids, and metal salts thereof; silyl;acrylates and metal salts thereof; sulfonyl or sulfonamide; andphosphates and phosphites. When M is a metal component, it may be anysuitable elemental metal available to those of ordinary skill in theart. Typically, the metal will be a transition metal, althoughpreferably it is tellurium or selenium.

It should be understood by those of ordinary skill in the art that thepresence of certain cis-to-trans catalysts according to the inventionmay require a larger amount of free-radical source, such as the amountsdescribed herein, compared to conventional cross-linking reactions.

In one embodiment, the ratio of the free radical source to thecis-to-trans catalyst is about 10 or less, preferably about 6 or less,more preferably about 4 or less, and even more preferably about 2 orless. In another embodiment, the ratio of the free radical source to thecis-to-trans catalyst is about 1 or less, preferably about 0.5 or less,and more preferably about 0.4 or less. In yet another embodiment, thefree radical source—cis-to-trans catalyst ratio is greater than 1,preferably about 1.5 or greater, and more preferably about 1.75 orgreater.

Methods of converting the cis-isomer of the base rubber to trans-isomerduring a molding cycle are provided in U.S. Patent Publication No.2003/0119989. For example, the base rubber, free-radical initiator,additional polymers, filler(s), and any other materials used in formingthe core may be combined to form a mixture by any type of mixing knownto one of ordinary skill in the art. Suitable types of mixing includesingle pass and multi-pass mixing, and the like. The crosslinking agent,and any other optional additives used to modify the characteristics ofthe golf ball core may similarly be combined by any type of mixing,however, a single-pass mixing process where ingredients are addedsequentially is preferred, as this type of mixing tends to increaseefficiency and reduce costs for the process.

In one embodiment, the mixing cycle is a single step where base rubber,cis-to-trans catalyst, filler, crosslinking agent, and peroxide areadded sequentially. Suitable mixing equipment is well known to those ofordinary skill in the art, and such equipment may include a Banburymixer, a two-roll mill, or a twin screw extruder. Although the curingtime depends on the various materials selected, a particularly suitablecuring time is about 5 to 18 minutes, preferably from about 8 to 15minutes, and more preferably from about 10 to 12 minutes. Those ofordinary skill in the art will be readily able to adjust the curing timeupward or downward based on the particular materials used and thediscussion herein.

Filler(s)

Fillers may be added to the compositions of the present invention andtypically include processing aids or compounds to affect Theological andmixing properties, the specific gravity (i.e., density-adjustingfillers), the modulus, the tear strength, reinforcement, and the like.The fillers are generally inorganic, and suitable fillers includenumerous metals, metal oxides and salts, such as zinc oxide and tinoxide, as well as barium sulfate, zinc sulfate, calcium carbonate, zinccarbonate, barium carbonate, clay, tungsten, tungsten carbide, an arrayof silicas, regrind (recycled core material typically ground to about 30mesh particle), high-Mooney-viscosity rubber regrind, and mixturesthereof.

In one embodiment, the composition includes a density-adjusting filler.Polymeric, ceramic, metal, or glass microspheres, or combinationsthereof, may be used to adjust the density or other properties of agiven layer, and such microspheres may be solid or hollow, and filled orunfilled. In one embodiment, the compositions of the invention includeabout 0.05 pph to about 1 pph of a density-adjusting filler. In anotherembodiment, about 0.1 pph to about 0.3 pph of density-adjusting filleris included in the compositions of the invention. In still anotherembodiment, the density-adjusting filler is present in an amount ofabout 0.1 pph to about 0.2 pph based on 100 parts of base rubber.

The amount of density-adjusting filler to be included in thecompositions of the invention may also be determined by the desiredspecific gravity of the golf ball component to be formed. For example,the composition may include a density-adjusting filler present in anamount sufficient to achieve a golf ball component specific gravity ofabout 1 or greater. In one embodiment, the filler is present in anamount sufficient to adjust the specific gravity of the golf ballcomponent to about 1.1 or greater. In another embodiment, the filler ispresent in an amount sufficient to adjust the specific gravity of thecomponent to about 1.13 or greater.

Accelerator(s)

When elemental sulfur or polymeric sulfur is included in thecis-to-trans catalyst, an accelerator may be used to improve theperformance of the cis-to-trans catalyst. Suitable accelerators include,but are not limited to, sulfenamide, such as N-oxydiethylene2-benzothiazole-sulfenamide, thiazole, such as benzothiazyl disulfide,dithiocarbamate, such as bismuth dimethyldithiocarbamate, thiuram, suchas tetrabenzyl thiuram disulfide, xanthate, such as zinc isopropylxanthate, thiadiazine, thiourea, such as trimethylthiourea, guanadine,such as N,N′-di-ortho-tolylguanadine, or aldehyde-amine, such as abutyraldehyde-aniline condensation product, or mixtures thereof.

Antioxidant

Typically, antioxidants are included in conventional rubber-based golfball component compositions because antioxidants are included in thematerials supplied by manufacturers of compounds used therein. Withoutbeing bound to any particular theory, higher amounts of antioxidant inthe reaction product may result in less trans-isomer content because theantioxidants consume at least a portion of the free radical source. Forexample, a polybutadiene reaction product with 0.5 pph of antioxidantcured at 335° F. for 11 minutes results in about 15 percent trans-isomercontent at an exterior surface of the center and about 13.4 percent atan interior location after the conversion reaction. In contrast, thesame polybutadiene reaction product substantially free of antioxidantsresults in about 32 percent trans-isomer content at an exterior surfaceand about 21.4 percent at an interior location after the conversionreaction.

Thus, even with high amounts of the free radical source in the reactionproduct described previously, such as for example about 3 pph, an amountof antioxidant greater than about 0.3 pph may significantly reduce theeffective amount of free radicals that are actually available to assistin a cis-to-trans conversion.

One way to ensure sufficient amounts of free radicals are provided forthe conversion is to increase the initial levels of free radicalspresent in the composition so that sufficient amounts of free radicalsremain after interaction with antioxidants in the composition. Thus, theinitial amount of free radicals provided in the composition may beincreased by at least about 10 percent, and more preferably areincreased by at least about 25 percent so that the effective amount ofremaining free radicals sufficient to adequately provide the desiredcis-to-trans conversion. Depending on the amount of antioxidant presentin the composition, the initial amount of free radicals may be increasedby at least 50 percent, 100 percent, or an even greater amount asneeded. As discussed below, selection of the amount of free radicals inthe composition may be determined based on a desired ratio of freeradicals to antioxidant.

Another approach is to reduce the levels of or completely eliminateantioxidants in the composition. For instance, the reaction product ofthe present invention may be substantially free of antioxidants, therebyachieving greater utilization of the free radicals toward thecis-to-trans conversion. As used herein, the term “substantially free”generally means that the polybutadiene reaction product includes lessthan about 0.3 pph of antioxidant, preferably less than about 0.1 pph ofantioxidant, more preferably less than about 0.05 pph of antioxidant,and most preferably about 0.01 pph or less antioxidant.

In one embodiment, the ratio of the free radical source to antioxidantis greater than about 10, preferably greater than about 25, and morepreferably greater than about 50. In another embodiment, the freeradical source-antioxidant ratio is about 100 or greater, preferablyabout 200 or greater, more preferably 250 or greater, and even morepreferably about 300 or greater.

If the compositions of the invention are substantially free ofantioxidants, the amount of the free radical source may be about 3 pphor less, preferably about 2.5 pph or less, and more preferably about 2.4pph or less. In one embodiment, the amount of the free radical source inthe composition is about 2 pph or less, preferably about 1.5 pph orless, and more preferably about 1 pph or less. When the compositioncontains about 0.05 pph or greater antioxidant, however, the freeradical source is preferably present in an amount of about 0.5 pph orgreater. In one embodiment, when the composition contains about 0.1 pphor greater antioxidant, the free radical source is present in an amountof about 2 pph or greater. In another embodiment, the free radicalsource is present in an amount of about 2.5 pph or greater when theantioxidant is present in an amount of about 0.1 pph or greater.

Composition Properties

The compositions of the invention preferably produce a golf ballcomponents having an Atti compression of about 70 or less. As usedherein, the term “Atti compression” is defined as the deflection of anobject or material relative to the deflection of a calibrated spring, asmeasured with an Atti Compression Gauge, that is commercially availablefrom Atti Engineering Corp. of Union City, N.J. Atti compression istypically used to measure the compression of a golf ball and/or a golfball component. Compression values are dependent on the diameter of thearticle being measured. In another embodiment, the compression of thecomponent is about 20 or greater. As used herein, the term “about” isused in connection with one or more numbers or numerical ranges, shouldbe understood to refer to all such numbers, including all numbers in arange. In still another embodiment, the compression of the component isabout 25 to about 65. In yet another embodiment, the componentcompression is about 30 to about 50.

In an alternative embodiment, the component may have a compression ofless than about 20, more preferably less than about 10, and mostpreferably around 0. As known to one of ordinary skill in the art,however, the compression of the component generated according to thepresent invention may be below the measurement of the Atti CompressionGauge.

Moreover, the composition preferably has a flexural modulus of fromabout 500 psi to about 300,000 psi, preferably from about 1,000 to about250,000, and more preferably from about 2,000 to about 200,000 psi.

Golf Ball Construction

The rubber-based compositions of the present invention may be used withany type of ball construction. For example, one-piece, two-piece,three-piece, and four-piece golf ball designs are contemplated by thepresent invention. In addition, golf balls having double cores,intermediate layer(s), and/or double covers are also useful with thepresent invention. As known to those of ordinary skill in the art, thetype of golf ball constructed, i.e., double core, double cover, and thelike, depends on the type of performance desired of the ball. As usedherein, the term “layer” includes any generally spherical portion of agolf ball, i.e., a golf ball core or center, an intermediate layer,and/or a golf ball cover. As used herein, the term “inner layer” refersto any golf ball layer beneath the outermost structural layer of thegolf ball. As used herein, “structural layer” does not include a coatinglayer, top coat, paint layer, or the like. As used herein, the term“multilayer” means at least two layers.

In one embodiment, a golf ball 2 according to the invention (as shown inFIG. 1) includes a core 4 and a cover 6, wherein the at least one ofcore 4 and cover 6 incorporates at least one layer including therubber-based composition of the invention. In another embodiment, thecore 4 is formed of the rubber-based composition of the invention.Similarly, FIG. 2 illustrates a golf ball according to the inventionincorporating an intermediate layer. Golf ball 10 includes a core 12, acover 16, and an intermediate layer 14 disposed between the core 12 andcover 16. Any of the core 12, intermediate layer 14, or cover 16 mayincorporate at least one layer that includes the rubber-basedcomposition of the invention. FIG. 3 illustrates a multilayer golf ball16 according to the invention including a large core 18, an outer corelayer, intermediate layer, or inner cover layer 20, and an outer coverlayer 22. Any of the core 18, outer core layer, intermediate layer, orinner cover layer 20, and outer cover layer 22 may include therubber-based compositions of the invention. FIG. 4 shows a four-piecegolf ball 24 according to the invention including a core 26, an outercore layer or intermediate layer 28, an inner cover layer 30, and anouter cover layer 32. Any of the core 26, outer core layer orintermediate layer 28, inner cover layer 30, and outer cover layer 32may include the rubber-based compositions of the invention.

Other non-limiting examples of suitable types of ball constructions thatmay be used with the present invention include those described in U.S.Pat. Nos. 6,056,842, 5,688,191, 5,713,801, 5,803,831, 5,885,172,5,919,100, 5,965,669, 5,981,654, 5,981,658, and 6,149,535, as well as inPublication Nos. U.S. 2001/0009310 A1, U.S. 2002/0025862, U.S.2002/0028885, U.S. 2002/0151380. The entire disclosures of these patentsand published patent applications are incorporated by reference herein.For example, in Publication No. U.S. 2002/015380, a golf ball havingthree or more cover layers is disclosed, of which any of the layers ofthe ball may be formed using the rubber-based compositions of theinvention. In addition, the compositions of the invention arecontemplated for use in layers of the gradated hardness multilayer golfballs disclosed in U.S. Patent Publication No. 2001/0005699, which isincorporated by reference herein in its entirety.

As discussed, the golf balls of the invention include at least onestructural layer that includes the rubber-based compositions of theinvention. In addition, as discussed below, the golf balls of theinvention may include core layers, intermediate layers, or cover layersformed from materials known to those of skill in the art. These examplesare not exhaustive, as skilled artisans would be aware that a variety ofmaterials might be used to produce a golf ball of the invention withdesired performance properties.

Core Layer(s)

The cores of the golf balls formed according to the invention may besolid, semi-solid, hollow, fluid-filled, or powder filled, but arepreferably solid and formed with the compositions of the invention. Asused herein, the term “core” means the innermost portion of a golf ball,and may include one or more layers. For example, U.S. Pat. Nos.6,180,040 and 6,180,722 disclose methods of preparing dual core golfballs. The entire disclosures of these patents are incorporated byreference herein. The term “semi-solid” as used herein refers to apaste, a gel, or the like. The cores of the golf balls of the inventionmay be spherical, cubical, pyramid-shaped, geodesic, or anythree-dimensional, symmetrical shape.

While the cores of the invention may be formed with the rubber-basedcompositions of the invention, conventional materials may also be usedto form the cores. Suitable core materials include, but are not limitedto, thermoset materials, such as rubber, styrene butadiene,polybutadiene, isoprene, polyisoprene, trans-isoprene, and polyurethane,and thermoplastic materials, such as conventional ionomer resins,polyamides, polyesters, and polyurethane. In one embodiment, at leastone layer of the core is formed from a polybutadiene reaction product,such as the reaction products disclosed in U.S. Patent Publication No.2003/0119989, the entire disclosure of which is incorporated byreference herein.

Additional materials may be included in the core layer compositionsoutlined above. For example, catalysts, coloring agents, opticalbrighteners, crosslinking agents, whitening agents such as TiO2 and ZnO,UV absorbers, hindered amine light stabilizers, defoaming agents,processing aids, surfactants, and other conventional additives may beadded to the core layer compositions of the invention. In addition,antioxidants, stabilizers, softening agents, plasticizers, includinginternal and external plasticizers, impact modifiers, foaming agents,density-adjusting fillers, reinforcing materials, and compatibilizersmay also be added to any of the core layer compositions. One of ordinaryskill in the art should be aware of the requisite amount for each typeof additive to realize the benefits of that particular additive.

The core may also include one or more wound layers (surrounding a fluidor solid center) including at least one tensioned elastomeric materialwound about the center. In one embodiment, the tensioned elastomericmaterial includes natural or synthetic elastomers or blends thereof. Thesynthetic elastomer preferably includes LYCRA. In another embodiment,the tensioned elastomeric material incorporates a polybutadiene reactionproduct as disclosed in co-pending U.S. Patent Publication No.2003/0119989. In yet another embodiment, the tensioned elastomericmaterial may also be formed from conventional polyisoprene. In stillanother embodiment, a polyurea composition (as disclosed in co-pendingU.S. Patent Publication No. 2003/0096936, which is incorporated byreference in its entirety by reference herein) is used to form thetensioned elastomeric material. In another embodiment, solvent spunpolyethers urea, as disclosed in U.S. Pat. No. 6,149,535, which isincorporated in its entirety by reference herein, is used to form thetensioned elastomeric material in an effort to achieve a smallercross-sectional area with multiple strands.

The tensioned elastomeric layer may also be a high tensile filamenthaving a tensile modulus of about 10,000 kpsi or greater, as disclosedin co-pending U.S. Patent Publication Nos. 2002/0160859 and2002/0160862, the entire disclosures of which are incorporated byreference herein.

In another aspect of the invention, the golf balls of the inventioninclude a thin, highly filled core layer, such as the ones disclosed inU.S. Pat. No. 6,494,795, which is incorporated by reference herein inits entirety. A thin, highly filled core layer allows the weight or massof the golf ball to be allocated radially relative to the centroid,thereby dictating the moment of inertia of the ball. When the weight isallocated radially toward the centroid, the moment of inertia isdecreased, and when the weight is allocated outward away from thecentroid, the moment of inertia is increased.

Intermediate Layer(s)

As used herein, “intermediate layer” includes any layer between theinnermost layer of the golf ball and the outermost layer of the golfball. Therefore, intermediate layers may also be referred to as outercore layers, inner cover layers, and the like. When the golf ball of thepresent invention includes an intermediate layer, this layer may beformed from the rubber-based compositions of the invention.

The intermediate layer may also be formed of conventional materialsknown to those of ordinary skill in the art, including various thermosetand thermoplastic materials, as well as blends thereof. For example, theintermediate layers of the golf ball of the invention may be formed withthe compositions of the invention. The intermediate layer may likewisebe formed, at least in part, from one or more homopolymeric orcopolymeric materials, such as vinyl resins, polyolefins, polyurethanes,polyureas, polyamides, acrylic resins, olefinic thermoplastic rubbers,block copolymers of styrene and butadiene, isoprene or ethylene-butylenerubber, copoly(ether-amide), polyphenylene oxide resins, thermoplasticpolyesters, ethylene, propylene, 1-butene or 1-hexene based homopolymersor copolymers, and the like.

The intermediate layer may also be formed from highly neutralizedpolymers such as those disclosed U.S. Patent Publication No.2001/0018375 and 2001/0019971, which are incorporated herein in theirentirety by express reference thereto; grafted and non-graftedmetallocene catalyzed polyolefins and polyamides, polyamide/ionomerblends, and polyamide/nonionomer blends, such as those disclosed in U.SPatent Publication No. 2003/0078348, which is incorporated by referenceherein in its entirety; among other polymers. Examples of other suitableintermediate layer materials include blends of some of the abovematerials, such as those disclosed in U.S. Pat. No. 5,688,181, theentire disclosure of which is incorporated by reference herein.

Additional materials may be included in the intermediate layercompositions outlined above. For example, catalysts, coloring agents,optical brighteners, crosslinking agents, whitening agents such as TiO2and ZnO, UV absorbers, hindered amine light stabilizers, defoamingagents, processing aids, surfactants, and other conventional additivesmay be added to the intermediate layer compositions of the invention. Inaddition, antioxidants, stabilizers, softening agents, plasticizers,including internal and external plasticizers, impact modifiers, foamingagents, density-adjusting fillers, reinforcing materials, andcompatibilizers may also be added to any of the intermediate layercompositions. One of ordinary skill in the art should be aware of therequisite amount for each type of additive to realize the benefits ofthat particular additive.

The intermediate layer may also be formed of a binding material and aninterstitial material distributed in the binding material, as discussedin U.S Patent Publication No. 2003/0125134, the entire disclosure ofwhich is incorporated by reference herein. In addition, at least oneintermediate layer may also be a moisture barrier layer, such as theones described in U.S. Pat. No. 5,820,488, which is incorporated in itsentirety by reference herein. The intermediate layer may also be formedfrom any of the polyurethane, polyurea, and polybutadiene materialsdiscussed co-pending U.S. Patent Publication No. 2003/0096936.

Cover Layer(s)

The cover provides the interface between the ball and a club. As usedherein, the term “cover” means the outermost portion of a golf ball. Acover typically includes at least one layer and may contain indentationssuch as dimples and/or ridges. Paints and/or laminates are typicallydisposed about the cover to protect the golf ball during use thereof.The cover may include a plurality of layers, e.g., an inner cover layerdisposed about a golf ball center and an outer cover layer formedthereon.

Inner and/or outer cover layers may be formed of the compositions of theinvention. Alternatively, both the inner and/or outer cover layers ofgolf balls of the present invention may be formed of the highlyneutralized ionomer compositions, other cover materials known to thoseof skill in the art, or blends thereof. For example, the cover may beformed of polyurea, polyurethane, or mixtures thereof, as disclosed inco-pending U.S. Patent Publication No. 2003/0096936 and U.S. patentapplication Ser. No. 10/339,603, filed Jan. 10, 2003, entitled“Polyurethane Compositions for Golf Balls.” The entire disclosures ofthese applications are incorporated by reference herein.

In addition, cover layers may also be formed of one or morehomopolymeric or copolymeric materials, such as vinyl resins,polyolefins, conventional polyurethanes and polyureas, such as the onesdisclosed in U.S. Pat. Nos. 5,334,673, and 5,484,870, polyamides,acrylic resins and blends of these resins with poly vinyl chloride,elastomers, and the like, thermoplastic urethanes, olefinic thermplasticrubbers, block copolymers of styrene and butadiene, polyphenylene oxideresins or blends of polyphenylene oxide with high impact polystyrene,thermoplastic polyesters, ethylene, propylene, 1-butene or 1-hexanebased homopolymers or copolymers including functional monomers, methylacrylate, methyl methacrylate homopolymers and copolymers, low acidionomers, high acid ionomers, alloys, and mixtures thereof. The covermay also be at least partially formed from a polybutadiene reactionproduct as disclosed in U.S. Patent Publication No. 2003/0119989.

Additional materials may be included in the cover layer compositionsoutlined above. For example, catalysts, coloring agents, opticalbrighteners, crosslinking agents, whitening agents such as TiO₂ and ZnO,UV absorbers, hindered amine light stabilizers, defoaming agents,processing aids, surfactants, and other conventional additives may beadded to the cover layer compositions of the invention. In addition,antioxidants, stabilizers, softening agents, plasticizers, includinginternal and external plasticizers, impact modifiers, foaming agents,density-adjusting fillers, reinforcing materials, and compatibilizersmay also be added to any of the cover layer compositions. Those ofordinary skill in the art should be aware of the requisite amount foreach type of additive to realize the benefits of that particularadditive.

In addition, while hardness gradients are typically used in a golf ballto achieve certain characteristics, the present invention alsocontemplates the compositions of the invention being used in a golf ballwith multiple cover layers having essentially the same hardness, whereinat least one of the layers has been modified in some way to alter aproperty that affects the performance of the ball. Such ballconstructions are disclosed in co-pending U.S. patent application Ser.No. 10/167,744, filed Jun. 13, 2002, entitled “Golf Ball with MultipleCover Layers,” the entire disclosure of which is incorporated byreference herein.

As discussed above with respect to the core of the golf balls of theinvention, the use of a thin, highly filled layer allows the weight ormass of the golf ball to be allocated radially relative to the centroid,thereby dictating the moment of inertia of the ball. This concept istranslatable to the cover layers of a golf ball. Thus, the inner coverlayer may be a thin, dense layer so as to form a high moment of inertiaball. In this aspect of the invention, the inner cover layer preferablyhas a specific gravity of greater than 1.2, more preferably more than1.5, even more preferably more than 1.8, and most preferably more than2.0. Suitable materials for the thin, dense layer include any materialthat meets the specific gravity stated above. For example, this thin,highly filled inner cover layer may be formed of the radiation-curablecompositions of the invention, adjusting for the requisite specificgravity. Alternatively, the inner cover layer may be formed fromepoxies, styrenated polyesters, polyurethanes or polyureas, liquidPBR's, silicones, silicate gels, agar gels, and the like.

Methods for Forming

The golf balls of the invention may be formed using a variety ofapplication techniques such as compression molding, flip molding,injection molding, retractable pin injection molding, reaction injectionmolding (RIM), liquid injection molding (LIM), casting, vacuum forming,powder coating, flow coating, spin coating, dipping, spraying, and thelike.

A method of injection molding using a split vent pin can be found inco-pending U.S. Patent Publication No. 2002/0079615 Examples ofretractable pin injection molding may be found in U.S. Pat. Nos.6,129,881, 6,235,230, and 6,379,138. These molding references areincorporated in their entirety by reference herein. In addition, achilled chamber, i.e., a cooling jacket, such as the one disclosed inU.S. patent application Ser. No. 09/717,136, filed Nov. 22, 2000,entitled “Method of Making Golf Balls” may be used to cool the castablecompositions, which also allows for a higher loading of catalyst (ifused) into the system.

One skilled in the art would appreciate that the molding method used maybe determined at least partially by the properties of the composition.For example, casting, RUM, or LIM may be preferred when the material isthermoset, whereas compression molding or injection molding may bepreferred for thermoplastic compositions.

Compression molding, however, may also be used for thermoset inner ballmaterials. For example, when cores are formed from a thermoset material,compression molding is a particularly suitable method of forming thecore, whereas when the cores are formed of a thermoplastic material, thecores may be injection molded. In addition, the intermediate layer mayalso be formed from using any suitable method known to those of ordinaryskill in the art. For example, an intermediate layer may be formed byblow molding and covered with a dimpled cover layer formed by injectionmolding, compression molding, casting, vacuum forming, powder coating,and the like.

In addition, when covers for the golf balls of the invention are formedof polyurea and/or polyurethane compositions, these materials may beapplied over an inner ball using a variety of application techniquessuch as spraying, compression molding, dipping, spin coating, casting,or flow coating methods that are well known in the art. Examples offorming polyurea and polyurethane materials about an inner ball aredisclosed in U.S. Pat. Nos. 5,733,428, 5,006,297, and 5,334,673, whichare incorporated by reference in their entirety herein. In oneembodiment, a combination of casting and compression molding can be usedto form a polyurethane or polyurea composition over an inner ball.However, the method of forming covers according to the invention is notlimited to the use of these techniques; other methods known to thoseskilled in the art may also be employed.

Any inner layer of the golf balls of the invention may be surfacetreated prior to cover formation to further increase the adhesionbetween the outer surface of the inner ball and the cover. In addition,the outermost cover of the golf balls of the invention may be surfacetreated prior to application of any coating layer. Such surfacetreatment may include mechanically or chemically abrading the outersurface of the subassembly. Additionally, the inner ball may besubjected to corona discharge, plasma treatment, and/or silane dippingprior to forming the cover around it. Other layers of the ball, e.g.,the core, also may be surface treated. Examples of these and othersurface treatment techniques can be found in U.S. Pat. No. 6,315,915,which is incorporated by reference in its entirety.

The methods discussed herein and other manufacturing methods for formingthe golf ball components of the present invention are also disclosed inU.S. Pat. Nos. 6,207,784 and 5,484,870, the disclosures of which areincorporated herein by reference in their entirety.

Dimples

The golf balls of the invention are preferably designed with certainflight characteristics in mind. The use of various dimple patterns andprofiles provides a relatively effective way to modify the aerodynamiccharacteristics of a golf ball. As such, the manner in which the dimplesare arranged on the surface of the ball can be by any available method.For instance, the ball may have an icosahedron-based pattern, such asdescribed in U.S. Pat. No. 4,560,168, or an octahedral-based dimplepatterns as described in U.S. Pat. No. 4,960,281. Alternatively, thedimple pattern can be arranged according to phyllotactic patterns, suchas described in U.S. Pat. No. 6,338,684, or a a tubular lattice pattern,such as the one disclosed in U.S. Pat. No. 6,290,615, the disclosures ofwhich are incorporated herein in their entirety.

Dimple patterns may also be based on Archimedean patterns including atruncated octahedron, a great rhombcuboctahedron, a truncateddodecahedron, and a great rhombicosidodecahedron, wherein the patternhas a non-linear parting line, as disclosed in U.S. patent applicationSer. No. 10/078,417, which is incorporated in its entirety by referenceherein. The golf balls of the present invention may also be covered withnon-circular shaped dimples, i.e., amorphous shaped dimples, asdisclosed in U.S. Pat. No. 6,409,615, which is incorporated in itsentirety by reference herein.

Dimple patterns that provide a high percentage of surface coverage arepreferred, and are well known in the art. For example, U.S. Pat. Nos.5,562,552, 5,575,477, 5,957,787, 5,249,804, and 4,925,193 disclosegeometric patterns for positioning dimples on a golf ball. In oneembodiment, the golf balls of the invention have a dimple coverage ofthe surface area of the cover of at least about 60 percent, preferablyat least about 65 percent, and more preferably at least 70 percent orgreater. Dimple patterns having even higher dimple coverage values mayalso be used with the present invention. Thus, the golf balls of thepresent invention may have a dimple coverage of at least about 75percent or greater, about 80 percent or greater, or even about 85percent or greater.

The golf balls of the present invention may also have a plurality ofpyramidal projections disposed on the intermediate layer of the ball, asdisclosed in U.S. Pat. No. 6,383,092, which is incorporated in itsentirety by reference herein. The plurality of pyramidal projections onthe golf ball may cover between about 20 percent to about 80 of thesurface of the intermediate layer. In an alternative embodiment, thegolf ball may have a non-planar parting line allowing for some of theplurality of pyramidal projections to be disposed about the equator.

Several additional non-limiting examples of dimple patterns with varyingsizes of dimples are also provided in U.S. Pat. Nos. 6,358,161 and6,213,898, the entire disclosures of which are incorporated by referenceherein.

The total number of dimples on the ball, or dimple count, may varydepending such factors as the sizes of the dimples and the patternselected. In general, the total number of dimples on the ball preferablyis between about 100 to about 1000 dimples, although one skilled in theart would recognize that differing dimple counts within this range cansignificantly alter the flight performance of the ball. In oneembodiment, the dimple count is about 380 dimples or greater, but morepreferably is about 400 dimples or greater, and even more preferably isabout 420 dimples or greater. In one embodiment, the dimple count on theball is about 422 dimples. In some cases, it may be desirable to havefewer dimples on the ball. Thus, one embodiment of the present inventionhas a dimple count of about 380 dimples or less, and more preferably isabout 350 dimples or less.

Dimple profiles revolving a catenary curve about its symmetrical axismay increase aerodynamic efficiency, provide a convenient way to alterthe dimples to adjust ball performance without changing the dimplepattern, and result in uniformly increased flight distance for golfersof all swing speeds. Thus, catenary curve dimple profiles, as disclosedin U.S. Patent Publication No. 2003/0114255, which is incorporated inits entirety by reference herein, is contemplated for use with the golfballs of the present invention.

Golf Ball Post-Processing

The golf balls of the present invention may be painted, coated, orsurface treated for further benefits. For example, a golf ball of theinvention may be treated with a base resin paint composition or thecover composition may contain certain additives to achieve a desiredcolor characteristic. In one embodiment, the golf ball cover compositioncontains a fluorescent whitening agent, e.g., a derivative of7-triazinylamino-3-phenylcoumarin, to provide improved weatherresistance and brightness. An example of such a fluorescent whiteningagent is disclosed in U.S. Patent Publication No. 2002/0082358, which isincorporated by reference herein in its entirety.

Protective and decorative coating materials, as well as methods ofapplying such materials to the surface of a golf ball cover are wellknown in the golf ball art. Generally, such coating materials compriseurethanes, urethane hybrids, epoxies, polyesters and acrylics. Ifdesired, more than one coating layer can be used. The coating layer(s)may be applied by any suitable method known to those of ordinary skillin the art. For example, the coating layer(s) may be applied to the golfball cover by an in-mold coating process, such as described in U.S. Pat.No. 5,849,168, which is incorporated in its entirety by referenceherein. The coating layer may have a thickness of about 0.004 inches orless, more preferably about 0.002 inches or less.

In addition, the golf balls of the invention may be painted or coatedwith an ultraviolet curable/treatable ink, by using the methods andmaterials disclosed in U.S. Pat. Nos. 6,500,495, 6,248,804, and6,099,415, the entire disclosures of which are incorporated by referenceherein.

In addition, trademarks or other indicia may be stamped, i.e.,pad-printed, on the outer surface of the ball cover, and the stampedouter surface is then treated with at least one clear coat to give theball a glossy finish and protect the indicia stamped on the cover.

The golf balls of the invention may also be subjected to dyesublimation, wherein at least one golf ball component is subjected to atleast one sublimating ink that migrates at a depth into the outersurface and forms an indicia. The at least one sublimating inkpreferably includes at least one of an azo dye, a nitroarylamine dye, oran anthraquinone dye. U.S. Patent Publication No. 20030106442, theentire disclosure of which is incorporated by reference herein.

Laser marking of a selected surface portion of a golf ball causing thelaser light-irradiated portion to change color is also contemplated foruse with the present invention. U.S. Pat. Nos. 5,248,878 and 6,075,223generally disclose such methods, the entire disclosures of which areincorporated by reference herein. In addition, the golf balls may besubjected to ablation, i.e., directing a beam of laser radiation onto aportion of the cover, irradiating the cover portion, wherein theirradiated cover portion is ablated to form a detectable mark, whereinno significant discoloration of the cover portion results therefrom.Ablation is discussed in U.S. Pat. No. 6,462,303, which is incorporatedin its entirety by reference herein.

Golf Ball Properties

The properties such as hardness, modulus, core diameter, intermediatelayer thickness and cover layer thickness of the golf balls of thepresent invention have been found to effect play characteristics such asspin, initial velocity and feel of the present golf balls. For example,the flexural and/or tensile modulus of the intermediate layer arebelieved to have an effect on the “feel” of the golf balls of thepresent invention. It should be understood that the ranges herein aremeant to be intermixed with each other, i.e., the low end of one rangemay be combined with a high end of another range.

Component Dimensions

Dimensions of golf ball components, i.e., thickness and diameter, mayvary depending on the desired properties. For the purposes of theinvention, any layer thickness may be employed. Non-limiting examples ofthe various embodiments outlined above are provided here with respect tolayer dimensions.

The present invention relates to golf balls of any size. While USGAspecifications limit the size of a competition golf ball to more than1.68 inches in diameter, golf balls of any size can be used for leisuregolf play. The preferred diameter of the golf balls is from about 1.68inches to about 1.8 inches. The more preferred diameter is from about1.68 inches to about 1.76 inches. A diameter of from about 1.68 inchesto about 1.74 inches is most preferred, however diameters anywhere inthe range of from 1.7 to about 1.95 inches can be used. Preferably, theoverall diameter of the core and all intermediate layers is about 80percent to about 98 percent of the overall diameter of the finishedball.

The core may have a diameter ranging from about 0.09 inches to about1.65 inches. In one embodiment, the diameter of the core of the presentinvention is about 1.2 inches to about 1.630 inches. In anotherembodiment, the diameter of the core is about 1.3 inches to about 1.6inches, preferably from about 1.39 inches to about 1.6 inches, and morepreferably from about 1.5 inches to about 1.6 inches. In yet anotherembodiment, the core has a diameter of about 1.55 inches to about 1.65inches.

The core of the golf ball may also be extremely large in relation to therest of the ball. For example, in one embodiment, the core makes upabout 90 percent to about 98 percent of the ball, preferably about 94percent to about 96 percent of the ball. In this embodiment, thediameter of the core is preferably about 1.54 inches or greater,preferably about 1.55 inches or greater. In one embodiment, the corediameter is about 1.59 inches or greater. In another embodiment, thediameter of the core is about 1.64 inches or less.

When the core includes an inner core layer and an outer core layer, theinner core layer is preferably about 0.9 inches or greater and the outercore layer preferably has a thickness of about 0.1 inches or greater. Inone embodiment, the inner core layer has a diameter from about 0.09inches to about 1.2 inches and the outer core layer has a thickness fromabout 0.1 inches to about 0.8 inches. In yet another embodiment, theinner core layer diameter is from about 0.095 inches to about 1.1 inchesand the outer core layer has a thickness of about 0.20 inches to about0.03 inches.

The cover typically has a thickness to provide sufficient strength, goodperformance characteristics, and durability. The thickness of the outercover layer may be from about 0.005 inches to about 0.100 inches,preferably about 0.007 inches to about 0.035 inches. In one embodiment,the cover thickness is from about 0.02 inches to about 0.35 inches. Inanother embodiment, the cover preferably has a thickness of about 0.02inches to about 0.12 inches, preferably about 0.1 inches or less, morepreferably about 0.07 inches or less. In yet another embodiment, theouter cover has a thickness from about 0.02 inches to about 0.07 inches.In still another embodiment, the cover thickness is about 0.05 inches orless, preferably from about 0.02 inches to about 0.05 inches. Forexample, the outer cover layer may be between about 0.02 inches andabout 0.045 inches, preferably about 0.025 inches to about 0.04 inchesthick. In one embodiment, the outer cover layer is about 0.03 inchesthick.

The range of thicknesses for an intermediate layer of a golf ball islarge because of the vast possibilities when using an intermediatelayer, i.e., as an outer core layer, an inner cover layer, a woundlayer, a moisture/vapor barrier layer. When used in a golf ball of theinvention, the intermediate layer, or inner cover layer, may have athickness about 0.3 inches or less. In one embodiment, the thickness ofthe intermediate layer is from about 0.002 inches to about 0.1 inches,preferably about 0.01 inches or greater. In one embodiment, thethickness of the intermediate layer is about 0.09 inches or less,preferably about 0.06 inches or less. In another embodiment, theintermediate layer thickness is about 0.05 inches or less, morepreferably about 0.01 inches to about 0.045 inches. In one embodiment,the intermediate layer, thickness is about 0.02 inches to about 0.04inches. In another embodiment, the intermediate layer thickness is fromabout 0.025 inches to about 0.035 inches. In yet another embodiment, thethickness of the intermediate layer is about 0.035 inches thick. Instill another embodiment, the inner cover layer is from about 0.03inches to about 0.035 inches thick. Varying combinations of these rangesof thickness for the intermediate and outer cover layers may be used incombination with other embodiments described herein.

The ratio of the thickness of the intermediate layer to the outer coverlayer is preferably about 10 or less, preferably from about 3 or less.In another embodiment, the ratio of the thickness of the intermediatelayer to the outer cover layer is about 1 or less.

Hardness

Most golf balls consist of layers having different hardnesses, e.g.,hardness gradients, to achieve desired performance characteristics. Thepresent invention contemplates golf balls having hardness gradientsbetween layers, as well as those golf balls with layers having the samehardness.

It should be understood, especially to one of ordinary skill in the art,that there is a fundamental difference between “material hardness” and“hardness, as measured directly on a golf ball.” Material hardness isdefined by the procedure set forth in ASTM-D2240 and generally involvesmeasuring the hardness of a flat “slab” or “button” formed of thematerial of which the hardness is to be measured. Hardness, whenmeasured directly on a golf ball (or other spherical surface) is acompletely different measurement and, therefore, results in a differenthardness value. This difference results from a number of factorsincluding, but not limited to, ball construction (i.e., core type,number of core and/or cover layers, etc.), ball (or sphere) diameter,and the material composition of adjacent layers. It should also beunderstood that the two measurement techniques are not linearly relatedand, therefore, one hardness value cannot easily be correlated to theother.

The cores of the present invention may have varying hardnesses dependingon the particular golf ball construction. In one embodiment, the corehardness is at least about 15 Shore A, preferably about 30 Shore A, asmeasured on a formed sphere. In another embodiment, the core has ahardness of about 50 Shore A to about 90 Shore D. In yet anotherembodiment, the hardness of the core is about 80 Shore D or less.Preferably, the core has a hardness about 30 to about 65 Shore D, andmore preferably, the core has a hardness about 35 to about 60 Shore D.

The intermediate layer(s) of the present invention may also vary inhardness depending on the specific construction of the ball. In oneembodiment, the hardness of the intermediate layer is about 30 Shore Dor greater. In another embodiment, the hardness of the intermediatelayer is about 90 Shore D or less, preferably about 80 Shore D or less,and more preferably about 70 Shore D or less. In yet another embodiment,the hardness of the intermediate layer is about 50 Shore D or greater,preferably about 55 Shore D or greater. In one embodiment, theintermediate layer hardness is from about 55 Shore D to about 65 ShoreD. The intermediate layer may also be about 65 Shore D or greater.

When the intermediate layer is intended to be harder than the corelayer, the ratio of the intermediate layer hardness to the core hardnesspreferably about 2 or less. In one embodiment, the ratio is about 1.8 orless. In yet another embodiment, the ratio is about 1.3 or less.

As with the core and intermediate layers, the cover hardness may varydepending on the construction and desired characteristics of the golfball. The ratio of cover hardness to inner ball hardness is a primaryvariable used to control the aerodynamics of a ball and, in particular,the spin of a ball. In general, the harder the inner ball, the greaterthe driver spin and the softer the cover, the greater the driver spin.

For example, when the intermediate layer is intended to be the hardestpoint in the ball, e.g., about 50 Shore D to about 75 Shore D, the covermaterial may have a hardness of about 20 Shore D or greater, preferablyabout 25 Shore D or greater, and more preferably about 30 Shore D orgreater, as measured on the slab. In another embodiment, the coveritself has a hardness of about 30 Shore D or greater. In particular, thecover may be from about 30 Shore D to about 70 Shore D. In oneembodiment, the cover has a hardness of about 40 Shore D to about 65Shore D, and in another embodiment, about 40 Shore to about 55 Shore D.In another aspect of the invention, the cover has a hardness less thanabout 45 Shore D, preferably less than about 40 Shore D, and morepreferably about 25 Shore D to about 40 Shore D. In one embodiment, thecover has a hardness from about 30 Shore D to about 40 Shore D.

In this embodiment when the outer cover layer is softer than theintermediate layer or inner cover layer, the ratio of the Shore Dhardness of the outer cover material to the intermediate layer materialis about 0.8 or less, preferably about 0.75 or less, and more preferablyabout 0.7 or less. In another embodiment, the ratio is about 0.5 orless, preferably about 0.45 or less.

In yet another embodiment, the ratio is about 0.1 or less when the coverand intermediate layer materials have hardnesses that are substantiallythe same. When the hardness differential between the cover layer and theintermediate layer is not intended to be as significant, the cover mayhave a hardness of about 55 Shore D to about 65 Shore D. In thisembodiment, the ratio of the Shore D hardness of the outer cover to theintermediate layer is about 1.0 or less, preferably about 0.9 or less.

In another embodiment, the cover layer is harder than the intermediatelayer. In this design, the ratio of Shore D hardness of the cover layerto the intermediate layer is about 1.33 or less, preferably from about1.14 or less.

Compression

Compression values are dependent on the diameter of the component beingmeasured. Atti compression is typically used to measure the compressionof a golf ball. As used herein, the terms “Atti compression” or“compression” are defined as the deflection of an object or materialrelative to the deflection of a calibrated spring, as measured with anAtti Compression Gauge, that is commercially available from AttiEngineering Corp. of Union City, N.J.

The Atti compression of the core, or portion of the core, of golf ballsprepared according to the invention is preferably less than about 80,more preferably less than about 75. In another embodiment, the corecompression is from about 40 to about 80, preferably from about 45 toabout 75, and more preferably from about 50 to about 70. In yet anotherembodiment, the core compression is preferably below about 50, and morepreferably below about 25. In an alternative, low compressionembodiment, the core has a compression less than about 20, morepreferably less than about 10, and most preferably, 0. As known to thoseof ordinary skill in the art, however, the cores generated according tothe present invention may be below the measurement of the AttiCompression Gauge.

In one embodiment, golf balls of the invention preferably have an Atticompression of about 55 or greater, preferably from about 60 to about120. In another embodiment, the Atti compression of the golf balls ofthe invention is at least about 40, preferably from about 50 to 120, andmore preferably from about 60 to 100. In yet another embodiment, thecompression of the golf balls of the invention is about 75 or greaterand about 95 or less. For example, a preferred golf ball of theinvention may have a compression from about 80 to about 95.

Initial Velocity and COR

There is currently no USGA limit on the COR of a golf ball, but theinitial velocity of the golf ball cannot exceed 250±5 feet/second(ft/s). Thus, in one embodiment, the initial velocity is about 245 ft/sor greater and about 255 ft/s or greater. In another embodiment, theinitial velocity is about 250 ft/s or greater. In one embodiment, theinitial velocity is about 253 ft/s to about 254 ft/s. In yet anotherembodiment, the initial velocity is about 255 ft/s. While the currentrules on initial velocity require that golf ball manufacturers staywithin the limit, one of ordinary skill in the art would appreciate thatthe golf ball of the invention would readily convert into a golf ballwith initial velocity outside of this range. For example, a golf ball ofthe invention may be designed to have an initial velocity of about 220ft/s or greater, preferably about 225 ft/s or greater.

As a result, of the initial velocity limitation set forth by the USGA,the goal is to maximize COR without violating the 255 ft/s limit. TheCOR of a ball is measured by taking the ratio of the outbound or reboundvelocity to the incoming or inbound velocity. In a one-piece solid golfball, the COR will depend on a variety of characteristics of the ball,including its composition and hardness. For a given composition, CORwill generally increase as hardness is increased. In a two-piece solidgolf ball, e.g., a core and a cover, one of the purposes of the cover isto produce a gain in COR over that of the core. When the contribution ofthe core to high COR is substantial, a lesser contribution is requiredfrom the cover. Similarly, when the cover contributes substantially tohigh COR of the ball, a lesser contribution is needed from the core.

The present invention contemplates golf balls having CORs from about0.700 to about 0.850 at an inbound velocity of about 125 ft/sec. In oneembodiment, the COR is about 0.750 or greater, preferably about 0.780 orgreater. In another embodiment, the ball has a COR of about 0.800 orgreater. In yet another embodiment, the COR of the balls of theinvention is about 0.800 to about 0.815.

In addition, the inner ball preferably has a COR of about 0.780 or more.In one embodiment, the COR is about 0.790 or greater.

Spin Rate

As known to those of ordinary skill in the art, the spin rate of a golfball will vary depending on the golf ball construction. In a multilayerball, e.g., a core, an intermediate layer, and a cover, wherein thecover is formed from the compositions of the invention, the spin rate ofthe ball off a driver (“driver spin rate”) may be 1500 rpm or greater.In one embodiment, the driver spin rate is about 2000 rpm to about 3500rpm. In another embodiment, the driver spin rate is about 2200 rpm toabout 3400 rpm. In still another embodiment, the driver spin rate may beless than about 1500 rpm.

Two-piece balls made according to the invention may also have driverspin rates of 1500 rpm and greater. In one embodiment, the driver spinrate is about 2000 rpm to about 3300 rpm. Wound balls made according tothe invention preferably have similar spin rates.

Methods of determining the spin rate should be well understood by thoseof ordinary skill in the art. Examples of methods for determining thespin rate are disclosed in U.S. Pat. Nos. 6,500,073, 6,488,591,6,286,364, and 6,241,622, which are incorporated by reference herein intheir entirety.

Flexural Modulus

Accordingly, it is preferable that the golf balls of the presentinvention have an intermediate layer with a flexural modulus of about500 psi to about 500,000 psi according to ASTM D-6272-98. Morepreferably, the flexural modulus of the intermediate layer is about1,000 psi to about 250,000 psi. Most preferably, the flexural modulus ofthe intermediate layer is about 2,000 psi to about 200,000 psi.

The flexural modulus of the cover layer is preferably about 2,000 psi orgreater, and more preferably about 5,000 psi or greater. In oneembodiment, the flexural modulus of the cover is from about 10,000 psito about 150,000 psi. More preferably, the flexural modulus of the coverlayer is about 15,000 psi to about 120,000 psi. Most preferably, theflexural modulus of the cover layer is about 18,000 psi to about 110,000psi. In another embodiment, the flexural modulus of the cover layer isabout 100,000 psi or less, preferably about 80,000 or less, and morepreferably about 70,000 psi or less. For example, the flexural modulusof the cover layer may be from about 10,000 psi to about 70,000 psi,from about 12,000 psi to about 60,000 psi, or from about 14,000 psi toabout 50,000 psi.

In one embodiment, when the cover layer has a hardness of about 50 ShoreD to about 60 Shore D, the cover layer preferably has a flexural modulusof about 55,000 psi to about 65,000 psi.

In one embodiment, the ratio of the flexural modulus of the intermediatelayer to the cover layer is about 0.003 to about 50. In anotherembodiment, the ratio of the flexural modulus of the intermediate layerto the cover layer is about 0.006 to about 4.5. In yet anotherembodiment, the ratio of the flexural modulus of the intermediate layerto the cover layer is about 0.11 to about 4.5.

In one embodiment, the compositions of the invention are used in a golfball with multiple cover layers having essentially the same hardness,but differences in flexural moduli. In this aspect of the invention, thedifference between the flexural moduli of the two cover layers ispreferably about 5,000 psi or less. In another embodiment, thedifference in flexural moduli is about 500 psi or greater. In yetanother embodiment, the difference in the flexural moduli between thetwo cover layers, wherein at least one is reinforced is about 500 psi toabout 10,000 psi, preferably from about 500 psi to about 5,000 psi. Inone embodiment, the difference in flexural moduli between the two coverlayers formed of unreinforced or unmodified materials is about 1,000 psito about 2,500 psi.

Specific Gravity

The specific gravity of a cover or intermediate layer is preferably atleast about 0.7. In one embodiment, the specific gravity of theintermediate layer or cover is about 0.8 or greater, preferably about0.9 or greater. For example, in one embodiment, the golf ball has anintermediate layer with a specific gravity of about 0.9 or greater and acover having a specific gravity of about 0.95 or greater. In anotherembodiment, the intermediate layer or cover has a specific gravoty ofabout 1.00 or greater. In yet another embodiment, the specific gravityof the intermediate layer or cover is about 1.05 or greater, preferablyabout 1.10 or greater.

The core may have a specific gravity of about 1.00 or greater,preferably 1.05 or greater. For example, a golf ball of the inventionmay have a core with a specific gravity of about 1.10 or greater and acover with a specific gravity of about 0.95 or greater.

While it is apparent that the invention disclosed herein is wellcalculated to fulfill the objects stated above, it will be appreciatedthat numerous modifications and embodiments may be devised by thoseskilled in the art. For example, while golf balls and golf ballcomponents are used as examples for articles incorporating thecompositions of the invention, other golf equipment may be formed fromthe compositions of the invention. In one embodiment, at least a portionof a golf shoe is formed from the composition of the invention. Inanother embodiment, the composition of the invention is used to form atleast a portion of a golf club. Therefore, it is intended that theappended claims cover all such modifications and embodiments that fallwithin the true spirit and scope of the present invention.

EXAMPLES

The following non-limiting example is merely illustrative of thepreferred embodiments of the present invention, and are not to beconstrued as limiting the invention, the scope of which is defined bythe appended claims. Parts are by weight unless otherwise indicated.

Example 1 Cores Made According to the Invention

The cores of multilayer balls were formed by compression molding a blendof the batch formulation set forth in Table 1 below.

TABLE 1 CORE BATCH FORMULATION Parts Per Hundred (pph) Material Formula1 Formula 2 Base Rubber Buna CB23¹ 100 pph 100 ZDA Masterbatch Mixtureof zinc 30.0 35.0 diacrylate, polybutadiene, and processing aidActivator Zinc Oxide 5.0 5.0 Organic Peroxide Trigonox 265² 0.53 0.53Initiator Density Adjusting Barium Sulfate to 1.15 to 1.15 Filler¹Commercially available from Bayer of Akron, OH. ²Available from AkzoNobel of Chicago, IL.

Five ZDA masterbatches (Control and A-D) were used to make Formulations1 and 2, which are provided in Table 2 below:

TABLE 2 ZDA MASTERBATCH FORMULATIONS Weight Percent Material Control A BC D Buna CB23 17 17 17 17 17 SR-526¹ 80 80 80 80 80 Polyethylene AfluxPE-11² 3 Wax Zinc Salt of Aktiplast PP³ 3 Unsaturated Fatty Acids HighStyrene Andrez 8000 3 Resins HSR⁴ Westco HSR⁵ 3 Balata TP-251 3 ¹SR-526contains 92 weight percent zinc diacrylate and 8 weight percent zincstearate. ^(2,3)Commercially available from Rhein Chemie of Trenton, NewJersey. ^(4,5)Commercially available from Western Reserve Chemical, Inc.of Stow, OH.

As shown in FIG. 5 and tabulated below in Table 3, the use of aconventional polyethylene as a processing aid in a zinc diacrylatemasterbatch results in a core with a lower COR as compared to similarcore formulations using different processing aids. For example, the useof a zinc salt of an unsaturated fatty acid in the ZDA masterbatchresults in a core COR about 0.006 to about 0.007 greater than that of acore formed with a ZDA masterbatch including polyethylene wax.

TABLE 3 RESULTANT CORE PROPERTIES Weight Percent Control A B C D FormulaFormula Formula Formula Formula Formula Formula Formula Formula FormulaProperties #1 #2 #1 #2 #1 #2 #1 #2 #1 #2 Compression 51 76 51 74 55 7251 72 50 72 COR @ 125 ft/s 0.783 0.800 0.790 0.806 0.788 0.801 0.7880.800 0.787 0.802

The invention described and claimed herein is not to be limited in scopeby the specific embodiments herein disclosed, since these embodimentsare intended as illustrations of several aspects of the invention. Anyequivalent embodiments are intended to be within the scope of thisinvention. Indeed, various modifications of the invention in addition tothose shown and described herein will become apparent to those skilledin the art from the foregoing description. For example, the compositionsof the present invention may be used in a variety of golf equipment, forexample, golf shoes for sole applications, as well as in inserts forgolf putters. Such modifications are also intended to fall within thescope of the appended claims.

1. A velocity-improving pastille for golf balls comprising:polybutadiene; a chemical peptizer comprising at least one sulfurcompound comprising at least one halogenated organosulfur compound; anda physical peptizer comprising at least one metallic salt of a fattyacid, high styrene resins, transpolyisoprene, transpolybutadiene, andmixtures thereof, wherein the pastille comprises about 50 weight percentto about 95 weight percent of chemical peptizer and about 50 weightpercent to about 5 weight percent of physical peptizer.
 2. The pastilleof claim 1, wherein the pastille comprises about 60 weight percent toabout 90 weight percent of the chemical peptizer and about 10 weightpercent to about 15 weight percent of physical peptizer.
 3. The pastilleof claim 2, wherein the pastille comprises about 70 weight percent toabout 80 weight percent of the chemical peptizer and about 11 weightpercent to about 13 weight percent of the physical peptizer.
 4. Thepastille of claim 1, wherein the polybutadiene is present in an amountof about 5 percent to about 30 percent by weight of the pastille.
 5. Thepastille of claim 1, wherein the metallic salt is selected from thegroup consisting of magnesium, calcium, zinc, aluminum, sodium, lithium,nickel, and mixtures thereof.
 6. The pastille of claim 1, wherein thefatty acid is oleic acid, stearic acid, or combinations thereof.
 7. Thepastille of claim 1, wherein the halogenated organosulfur compound hasthe general formula:

where R₁–R₅ are selected from the group consisting of C₁–C₈ alkylgroups; halogen groups; thiol groups (—-SH), carboxylated groups;sulfonated groups; hydrogen; pentafluorothiophenol; 2-fluorothiophenol;3 -fluorothiophenol; 4-fluorothiophenol; 2,3-fluorothiophenol;2,4-fluorothiophenol; 3,4-fluorothiophenol; 3,5-fluorothiophenol2,3,4-fluorothiophenol; 3,4,5-fluorothiophenol;2,3,4,5-tetrafluorothiophenol; 2,3,5,6-tetrafluorothiophenol;4-chlorotetrafluorothiophenol; pentachiorothiophenol;2-chlorothiophenol; 3-chlorothiophenol; 4-chlorothiophenol;2,3-chlorothiophenol; 2,4-chlorothiophenol; 3,4-chlorothiophenol;3,5-chlorothiophenol; 2,3,4-chlorothiophenol; 3,4,5-chlorothiophenol;2,3,4,5-tetrachlorothiophenol; 2,3,5,6-tetrachlorothiophenol;pentabromothiophenol; 2-bromothiophenol; 3-bromothiophenol;4-bromothiophenol; 2,3-bromothiophenol; 2,4-bromothiophenol;3,4-bromothiophenol; 3,5-bromothiophenol; 2,3,4-bromothiophenol;3,4,5-bromothiophenol; 2,3,4,5-tetrabromothiophenol;2,3,5,6-tetrabromothiophenol; pentaiodothiophenol; 2-iodothiophenol; 3-iodothiophenol; 4-iodothiophenol; 2,3-iodothiophenol;2,4-iodothiophenol; 3,4-iodothiophenol; 3,5-iodothiophenol;2,3,4-iodothiophenol; 3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol;2,3,5,6-tetraiodothiophenoland; metal salts thereof, and mixturesthereof.
 8. The pastille of claim 1, wherein the halogenatedorganosulfur compound is zinc pentachlorothiophenol.
 9. A golf ballcomprising a core and a cover, wherein the core comprises avelocity-improving pastille comprising: a chemical peptizer comprisingat least one sulfur compound comprising at least one halogenatedorganosulfur compound; and a physical peptizer comprising at least onemetallic salt of a fatty acid, wherein the pastille comprises about 50weight percent to about 95 weight percent of chemical peptizer and about50 weight percent to about 5 weight percent of physical peptizer. 10.The golf ball of claim 9, wherein the physical peptizer comprises zincstearate, zinc oleate, or mixtures thereof.
 11. The golf ball of claim9, wherein the chemical peptizer comprises a zinc salt ofpentachlorothiophenol.
 12. The golf ball of claim 9, wherein the corecomposition further comprises a base rubber, at least one crosslinkingagent, and at least one free radical initiator.
 13. The golf ball ofclaim 12, wherein the core composition further comprises a least one ofan antioxidant and a density-adjusting filler.
 14. The golf ball ofclaim 9, wherein the pastille comprises about 60 percent to about 90percent of the chemical peptizer and about 10 percent to about 15percent of the physical peptizer.
 15. The golf ball of claim 9, whereinthe halogenated organosulfur compound has the general formula:

where R₁–R₅ are selected from the group consisting of C₁–C₈ alkylgroups; halogen groups; thiol groups (—SH), carboxylated groups;sulfonated groups; hydrogen; pentafluorothiophenol; 2-fluorothiophenol;3-fluorothiophenol; 4-fluorothiophenol; 2,3-fluorothiophenol;2,4-fluorothiophenol; 3,4-fluorothiophenol; 3,5-fluorothiophenol2,3,4-fluorothiophenol; 3,4,5-fluorothiophenol;2,3,4,5-tetrafluorothiophenol; 2,3,5,6-tetrafluorothiophenol;4-chlorotetrafluorothiophenol; pentachlorothiophenol;2-chlorothiophenol; 3-chlorothiophenol; 4-chlorothiophenol;2,3-chlorothiophenol; 2,4-chlorothiophenol; 3,4-chlorothiophenol;3,5-chlorothiophenol; 2,3,4-chlorothiophenol; 3,4,5-chlorothiophenol;2,3,4,5-tetrachlorothiophenol; 2,3,5,6-tetrachlorothiophenol;pentabromothiophenol; 2-bromothiophenol; 3-bromothiophenol;4-bromothiophenol; 2,3-bromothiophenol; 2,4-bromothiophenol;3,4-bromothiophenol; 3,5-bromothiophenol; 2,3,4-bromothiophenol;3,4,5-bromothiophenol; 2,3,4,5-tetrabromothiophenol;2,3,5,6-tetrabromothiophenol; pentaiodothiophenol; 2-iodothiophenol;3-iodothiophenol; 4-iodothiophenol; 2,3-iodothiophenol;2,4-iodothiophenol; 3,4-iodothiophenol; 3,5-iodothiophenol;2,3,4-iodothiophenol; 3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol;2,3,5,6-tetraiodothiophenoland; metal salts thereof; and mixturesthereof.
 16. A method of preparing a golf ball comprising: preparing avelocity-improving pastille comprising the steps of providing a chemicalpeptizer comprising at least one halogenated organosulfur compound;providing a physical peptizer comprising at least one metallic salt of afatty acid; and blending the chemical peptizer and physical peptizerwith polybutadiene in a mixer at a temperature of about 175° F. to about250° F. to form a pellet, preparing a composition including the pellet;forming at least a portion of the golf ball from the composition. 17.The method of claim 16, wherein the at least one sulfur compound is azinc salt of:

where R₁–R₅ is selected from the group consisting of C₁–C₈ alkyl groups;halogen groups; thiol groups (—SH), carboxylated groups; sulfonatedgroups; hydrogen; pentafluorothiophenol; 2-fluorothiophenol;3-fluorothiophenol; 4-fluorothiophenol; 2,3-fluorothiophenol;2,4-fluorothiophenol; 3,4-fluorothiophenol; 3,5-fluorothiophenol2,3,4-fluorothiophenol; 3,4,5-fluorothiophenol;2,3,4,5-tetrafluorothiophenol; 2,3,5,6-tetrafluorothiophenol;4-chlorotetrafluorothiophenol; pentachlorothiophenol;2-chlorothiophenol; 3-chlorothiophenol; 4-chlorothiophenol;2,3-chlorothiophenol; 2,4-chlorothiophenol; 3,4-chlorothiophenol;3,5-chlorothiophenol; 2,3,4-chlorothiophenol; 3,4,5-chlorothiophenol;2,3,4,5-tetrachlorothiophenol; 2,3,5,6-tetrachlorothiophenol;pentabromothiophenol; 2-bromothiophenol; 3-bromothiophenol;4-bromothiophenol; 2,3-bromothiophenol; 2,4-bromothiophenol;3,4-bromothiophenol; 3,5-bromothiophenol; 2,3,4-bromothiophenol;3,4,5-bromothiophenol; 2,3,4,5-tetrabromothiophenol;2,3,5,6-tetrabromothiophenol; pentaiodothiophenol; 2-iodothiophenol;3-iodothiophenol; 4-iodothiophenol; 2,3-iodothiophenol;2,4-iodothiophenol; 3,4-iodothiophenol; 3,5-iodothiophenol;2,3,4-iodothiophenol; 3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol;2,3,5,6-tetraiodothiophenoland; metal salts thereof and mixturesthereof.
 18. The method of claim 16, wherein the physical peptizercomprises zinc stearate, zinc oleate, or mixtures thereof.
 19. Themethod of claim 16, wherein the step of blending is performed at atemperature of about 200° F. to about 225° F.
 20. The method of claim16, wherein the step of blending further comprises blending about 50percent to about 95 percent chemical peptizer with about 50 percent toabout 5 percent physical peptizer.
 21. The method of claim 17, whereinthe at least one sulfur compound is a zinc salt ofpentachiorothiophenol.